Issued  January  29,  1907. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY.— BULLETIN  No.  92. 
A.  D.  MELVIN,  CHIEF  OF  BUREAU. 


8  Sf :  MILKING  MACHINE  AS  A  FACTOR  IN 

DAIRYING. 

I 

(A    PRELIMINARY    REPORT.) 

7  = 

I.— PRACTICAL  STUDIES  OF  A  MILKING  MACHINE. 

BY 

C.  B.  LANE,  B.  S., 

Assistant  Chief,  Dairy  Division,  Bureau  of  Animal  Industry. 


II.— BACTERIOLOGICAL  STUDIES  OF  A  MILKING  MACHINE. 

BY 

W.  A.  STOCKING,  JR.,  M.  S.  A., 

Bacteriologist  <  Storrs  Agricultural  Experiment  Station, 
Professor  of  Dairy  Bacteriology ,  Connecticut 
Agricultural  College. 


WASHINGTON: 

GOVERNMENT    PRINTING   OFFICE. 
1907. 


Issued  January  29,  1907. 

U.  S.   DEPARTMENT   OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY  — BUU.I-TIN  No.  92. 

A.  D    MHI.VIN,  Oin>   .,>.   BUREAU. 


THE  MILKING  MACHINE  AS  A  FACTOR  IN 

DAIRYING. 

(A    PRELIMINARY    REPORT.) 


—PRACTICAL  STUDIES  OF  A  MILKING  MACHINE. 

BY 

C.  B.  LANK,  B.  S., 

ssistant  Chief,  Dairy  Dii'isiou,  Bureau  of  Animal  Industry. 


II.— BACTERIOLOGICAL  STUDIES  OF  A  MILKING  MACHINE. 

BY 

W.  A.  STOCKING,  JR.,  M.  S.  A.. 

Bacteriologist ,  Starrs  Agricultural  Experiment  Station, 
Professor  of  Dairv  Bacteriology,  Connecticut 
Agricit  I  tn  ral  Co  liege. 


WASHINGTON: 

GOVERNMENT    PRINTING    OEEICE. 
!c>07. 


BUREAU  OF  ANIMAL  INDUSTRY. 


Chief:  A.  IX  MEI.VIN. 
Assistant  Chief:  A.  M.  FARKINGTON. 
Chief  C/erl:-  K.  B.  JONES. 
Biocliemic  Dieision:  MARION  DORSET,  chief. 

Dairy  Dirisiun:  Ki>.  II.  WEHSTER,  chief;  C.  B.  LANE,  assistant  chief. 
Inspection  Division:  HICK  P.  STEDDOM,  chief;  U.  (7.  HOTCK,  associate  chief;  MORRIS 
WOODEN,  assistant  chief. 

Pathological  Dirislon:  JOHN  R.  MOHLER,  chief. 

Quarantine  Dieision:  RICHARD  W.  HICKMAN,  chief. 

Division  of  Zoology:  BRAYTOX  II.  RANSOM,  chief. 

Experiment  Station:  F.  C.  SCHROEDER,  superintendent;  AY.  E.  COTTON,  assistant. 

Animal  Husbandman:  (!EORGE  M.  ROMMEL. 

Editor:  JAMES  M.  PICKENS. 


DAIRY    DIVISION. 

Chief:  Fd.  II.  Webster. 
Assistant  Chief:  C.  B.  Lane. 
Assistant:  Win.  Hart  Dexter. 


Butter  investigations:  C.  F.  (Tray,  cliemist,  in  charge;  C.  W.  Fryhofer,  assistant; 
E.  A.  McDonald,  W.  S.  Sinarzo,  W.  J.  Credicott,  market  inspectors. 

Market  mill:  investigations:  C.  B.  Lane,  assistant  chief,  in  charge;  R.  II.  Shaw, 
chemist;  (ieorge  M.  Whitaker,  Fllis  M.  Santee,  Ivan  C.  Weld,  assistants. 

Cheese  investigations:  C.  F.  Doane,  expert,  in  charge.  American  varieties:  John  L. 
Sammis,  chemist:  Jay  W.  Moore,  expert  maker.  European  varieties:  Charles 
Thorn,  mycologist;  Arthur  W.  Dox,  cliemist;  T.  W.  Issajeff,  expert  maker. 

Southern  dairy  investigations:  B.  H.  Rawl,  expert,  in  charge;  II.  N.  Slater,  Duncan 
Stuart,  J.  A.  Conover,  S.  E.  Barnes,  J.  W.  Ridgway,  J.  F.  Dorman,  assistants. 

Building  and  management  investigations:  B.  D.  White,  expert,  in  charge;  IT.  II. 
Parks,  architect;  W.  J.  Latimer,  Joseph  A.  Lockie,  assistants. 

Dairy  laboratories:  L.  A.  Rogers,  bacteriological  chemist,  in  charge. 

INSI'ECTIOX    STAFF. 

Henorated  butter  factories:  M.  W.  Fang,  510  Northwestern  Building,  Chicago,  111., 
in  charge. 

liennrated  butter  markets:  Levi  Weils,  Laceyville,  Pa.,  in  charge. 

Inapcctors:  Robert  McAdam,  510  Northwestern  Building,  Chicago.  111.;  (ieonre  M. 
Whitaker,  Washington,  D.  C. ;  F.  A.  McDonald,  Seattle,  Wash. 

Deimtij  inspector*:  S.  1!.  AYillis,  Boston,  Mass.;  R.  A.  McBride,  J.  II.  Barrett, 
(i  Harrison  street,  New  York,  N.  Y.;  II.  P.  Olsen,  St.  Paul,  Minn. 


LETTER  OF  TRANSMITTAL. 


U.  S.   DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY, 

Wash! ny ton,  D.  <?.,  Oriole  JJ,  MOV. 

SIR:  I  have  the  honor  to  transmit  herewith  a  preliminary  report  on 
"The  Milking-  Machine  as  a  Factor  in  Dairying."  an  investigation  of 
this  .subject  by  the  Dairy  Division  having  been  authorized  by  you. 
The  tirst  part  deals  with  the  practical  side  and  the  second  part  with 
the  bacteriological  pha.se  of  the  .subject. 

Recent  improvements  in  milking  machines  have  led  to  their  intro- 
duction and  practical  use  in  some  of  the  larger  dairies  of  the  country, 
and  there  are  indications  that  these  machines  may  come  into  general 
use  in  the  near  future  and  become  an  important  economic  factor  in 
the  dairy  industry.  While  the  investigations  so  far  made  have  been 
too  limited  to  justify  any  sweeping  deductions  or  positive  conclusions, 
it  is  believed,  in  view  of  the  importance  and  present  interest  of  the 
subject  to  dairymen,  that  the  results  here  presented  are  of  sufficient 
value  to  warrant  their  publication,  and  I  therefore  recommend  the 
publication  of  this  report  as  Bulletin  No.  '.»:>  in  the  series  of  this 
Bureau.  The  investigations  will  be  continued  and  further  results  may 
Ite  reported  later. 

The  experimental  work  which  is  the  basis  of  this  bulletin  was  con- 
ducted in  August,  1905.  but  owing  to  unavoidable  delays  the  manu- 
script has  not  been  ready  for  publication  until  now. 

Respectfully.  A.  P.  MELVIN, 

C  '/i  l<f  <>f  Bv.r<-<i  >/. 

Hon.  JAMES  WILSON. 

^t-rt'ctni'i/  of  Ayr!c>dtur<-. 

3 


CONTENTS. 


1.— PRACTICAL  STTIUKS  OF  A   MILKING   MACHINE. 

Page 

Introduction !l 

Some  milking  machines  in  use 10 

A  foot-power  milker 11 

A  power  milker  : 11 

A  milker  designed  for  either  hand  or  power \'2 

The  machine  used  in  the  investigations 1  - 

Cost  of  equipment  for  machine  milking !•''> 

Different  kinds  of  power  which  may  he  utili/ed b'^> 

Experiments  in  which  hand  and  machine  milking  were  compared 14 

Experiment  No.  1 14 

Time  required  for  hand  and  machine  milking  compared   17 

Yield  of  milk  from  hand  and  machine  milking  compared 18 

Thoroness  of  hand  and  machine  milking  compared -0 

Experiment  No.  '1 20 

Time  required  for  hand  and  machine  milking  compared 24 

Yield  of  milk  from  hand  and  machine  milking  compared '24 

Thoroness  of  hand  and  machine  milking  compared 1'5 

Quality  of  the  milk 1'ti 

General  considerations. -7 

Effects  of  milking  machines  upon  the  cows '27 

Adjusting  the  machines  to  the  cows l'S 

Practicability  of  using  machines  f< >r  large  and  small  herds -!' 

How  the  general   introduction   of  the  milking  machine  would  affect  the 

dairy  industry ...  L'i* 

Suggestions  for  improvements l_'!l 

Objections  and  ditliculties •'-() 

Need  for  further  investigations ol 

Results  of  experience  with  milkintr  machines  as  reported  by  dairymen .'>!' 

Addendum '•'>- 

II.  —  BACTERIOLOGICAL  STI'IdLS  <>K   A    MILKING    MACHINE. 

Production  of  sanitary  milk '•'>'•'> 

Experiments  designed  to  test  the  sanitary  character  of  machine-drawn  milk..  :14 

Experiments  at  Farm  No.   1 .'14 

Method  of  experiment. -'!4 

First  treatment  of  the  milking  machine- l!ii 

Second  treat  ment  of  the  machines :>7 

Third  treatment  of  the  machines 40 

Eourth  treatment  of  the  machines 41 

Fifth  treatment  of  the  machines 41 

Sixth  treatment  of  the  machines .  44 

Keeping  qualities  of  the  milk 44 

Summary  of  experiments  at  Farm  No.  1 .    _    .. . 4"> 


6  CONTENTS. 

Experiments  to  tost,  the  sanitary  character  of  machine-drawn  milk — Cont'd.  Page. 

Experiments  at  Farm  No.  2 46 

Method  of  experiment 46 

First  treatment  of  the  machines 47 

Second  treatment  of  the  machines 48 

Third  treatment  of  the  machines 49 

Fourth  treatment  of  the  machines 50 

Fifth  treatment  of  the  machines 52 

Sixth  treatment  of  the  machines 52 

Keeping  qualities  of  the  milk 54 

Summary  ( if  results  of  bacteriological  investigations 54 


ILLUSTRATIONS. 


Page. 
PI.ATK   I.   Kiy.    1.   A  foot-power  milker  with  attachments.     Fi<r.  2.  The  same 

machine  in  operation 12 

'2.    Fi<r.    1.   A  power   milker   with    attachments.       Fi<r.    "2.    The   same 

machine  in  operation \'2 

o.   Fi>r.   1.   Milking  machine  for  use  with  either  hand  or  power.     Fi«r.  2. 

Same  machine  in  operation 12 

4.   Fig.    1.   Milking  machine  used  in  experiments.      Fi*r.  2.   The  same 

machine  in  operation 12 


Fi<;.  1.   Bacteria  in  atmosphere  of  barn  at  farm  No.  1 .'!."> 

2.  Bacteria  in  machine-drawn  milk  in  experiment  Xo.  :!7 

3.  Bacteria  in  machine-drawn  milk  in  experiment  No.  101 

4.  Bacteria  in  milk  drawn   liy  steam-sterilized   machine  in  experiment 

Xo.  101 A ., -12 

5.  Bacteria  in  machine-drawn  milk  in  experiment  No.  10,'! J;i 

6.  Bacteria  in  atmosphere  of  Uirn  at  farm  No.  2 4H 


THE  MILKING  MACHINE  AS  A  FACTOR  IN  DAIRYING. 


.—PRACTICAL  STUDIES  OF  A  MILKING  MACHINE. 

By  ('.  B.  .LANK,  B.  S. 
Assistant  Chief,  Dairy  I)iris!on,  Bureau  of  Animal  Industry. 


INTRODUCTION. 

For  more  than  a  quarter  of  a  century  machinery  has  been  success- 
fully used  in  separating  the  cream  from  the  milk  and  churning  it  into 
butter,  but  a  machine  for  milking  the  cows  has  been  more  difficult  to 
supply.  It  has  long  been  realized  that  a  successful  and  practical  cow 
milker  would  mean  a  profitable  revolution  of  the  dairy  industry,  as  it 
would  render  the  work  of  milking  much  easier  and  reduce  the  necessity 
for  hired  help,  thus  making  the  dairyman  more  independent.  Efforts 
have  been  made  by  scores  of  inventors  for  more  than  half  a  centuiy 
to  construct  a  machine  that  would  milk  cows  in  a  satisfactory  manner 
and  without  injury.  The  German  writer  Martiny  states  that  ^  dif- 
ferent milking  machines  known  to  him  had  been  patented  in  different 
countries  or  mentioned  in  the  dairy  literature  between  the  years  1S77 
and  1898. 

The  annual  reports  of  the  United  States  Commissioner  of  Patents 
show  that  during  the  period  of  84  years  from  1.S72  to  I'.Hjf),  inclusive, 
127  patents  were  taken  out  in  this  country  alone  for  milking  machines 
or  separate  parts  of  them.  A  number  of  machines  have  been  success- 
ful in  extracting  the  milk  from  the  cow  by  either  pressure  or  suction, 
or  by  the  two  combined,  but  have  fallen  short  of  being  practical  in 
some  vital  point.  Naturally,  inventors  have  attempted  to  imitate  the 
wa}T  in  which  the  calf  sucks  its  dam.  The  difficulty  has  been  to 
reproduce  the  peculiar  influence  which  the  sucking  calf  has  upon  the 
cow  and  to  devi.se  a  machine  which  will  not  irritate  the  animal  and 
which  will  do  its  work  without  injury.  Another  difficulty  in  devising 
a  cow  milker  has  been  to  construct  it  so  that  it  could  be  adjusted  to  all 
cowrs.  Individual  animals  vary  greatly  in  the  si/e  and  conformation 
of  their  udders,  and  even  the  same  cow  varies  somewhat  in  the  si/e 
and  shape  of  her  udder  and  teats  during  the  different  stages  of  her 
11522— Xo.  (J2— 07 2  9 


10          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

lactation  period.  Cows  also  vary  greatly  in  disposition  and  temper- 
ament. A  successful  cow  milker,  therefore,  must  meet  all  these 
different  conditions.  Since  milking  must  necessarily  he  an  artificial 
process,  it  has  been  thought  for  some  time  that  animals  would  become 
accustomed  to  being  milked  by  machinery  just  the  same  as  the}' 
become  accustomed  to  hand  milking,  provided  a  milking  machine 
could  be  perfected  that  would  be  comfortable  to  the  animal  when  in 
operation.  A  heifer,  for  example,  coming  into  milk  the  first  time 
would  take  as  readily  to  one  artificial  method  as  to  another,  other 
things  being  equal. 

While  no  milking  machine  yet  invented  has  shown  its  practical 
value  in  a  way  that  has  led  to  its  general  use,  recent  improvements  in 
machines  of  this  type  have  resulted  in  greater  simplicity  of  construction 
and  effectiveness  in  operation,  and  consequently  they  are  in  practical 
use  in  a  limited  number  of  the  larger  dairies.  Indeed,  the  prospect  for 
the  general  introduction  of  milking  machines  appears  to  be  so  favor- 
able that  it  was  thought  advisable  by  the  Secretary  of  Agriculture  to 
authorize  an  investigation  of  the  fundamental  problems  involved  in 
the  use  of  such  machines.  These  fundamental  problems  may  be  stated 
as  follows:  (1)  The  practicability  of  substituting  machine  for  hand 
milking  in  the  actual  operations  of  dairying:  ('2)  the  effects  of  machine 
milking  on  the  quantity  and  composition  of  the  milk  yielded  by  the 
cows;  (3)  the  effects  of  machine  milking  on  the  cleanliness,  sanitary 
character,  and  keeping  qualities  of  the  milk. 

In  making  such  an  investigation  it  was,  of  course,  necessary  to 
select  some  machine  for  use.  The  machine  selected  is  OIK-  which 
was  found  to  be  in  actual  use  in  a  number  of  dairies,  and  one  which 
appeared  to  offer  adequate  means  for  conducting  the  proposed  inves- 
tigation. Its  selection  was  not  intended  as  in  anv  sense  a  recom- 

o  • 

mendation  of  this  particular  machine  to  the  favor  of  dairymen.  It  is 
believed,  however,  that,  in  so  far  as  the  investigation  has  demonstrated 
the  merits  of  this  machine,  it  will  benefit  all  inventors  and  manufac- 
turers of  successful  milking  machines. 

The  authors  fully  appreciate  the  fact  that  these  investigations  have 
been  too  limited  to  justify  any  .-weeping  deductions  or  positive  con- 
clusions. But  in  view  of  the  probable  general  introduction  of  such 
machinery  in  the  near  future,  it  is  believed  the  results  of  the  investi- 
gations are  of  sufficient  value  to  justify  their  publication. 

SOME  MILKING  MACHINES  IN  USE. 

As  a  complete  account  is  hereinafter  given  of  the  machine  used  in 
the  investigation,  a  brief  description  will  suHice  for  the  other  machines 
presented  here,  none  of  which  were  used  in  this  investigation,  and  in 
regard  to  the  efficiency  of  which  no  opinion  can  consequently  be 
exprest. 


SOME    MILKING    MACHINES.  11 

A    FOOT-POWER    MILKER. 

This  machine  (pi.  1)  is  designed  for  use  in  small  herds  and  has  no  sta- 
tionary fixtures.  It  consists  of  a  suction  pump  worked  by  foot  power, 
2  pieces  of  rubber  hose,  and  S  suction  cups  to  be  attached  to  the  teats 
of  the  2  cows,  which  can  be  milked  at  the  same  time.  The  milk  passes 
thru  the  cylinder,  and  also  thru  the  valve  in  the  pump  piston  itself. 
The  operator  sits  between  the  2  cows  and  works  the  pump  with  his 
feet.  On  opening-  the  spigot  the  suction  rapidly  draws  the  cups  over 
the  teats  and  the  milk  begins  to  flow  into  the  milk  pail,  which  is  hung 
on  the  spout  of  the  pump. 

The  teat  cups  are  hollow  and  conical.  Nearly  an  inch  from  the 
largo  end  the  cup  is  almost  closed  by  a  soft  rubber  diaphragm;  this 
disk,  being  elastic,  fits  air-tight  around  the  different-sized  teats.  The 
teats  rill  the  conical  cup  except  at  the  small  end  where  suction  is 
applied.  The  cup  is  made  of  three  pieces  of  smooth  hard  rubber.  To 
the  end  of  the  cup  is  attached  a  piece  of  glass  tubing  thru  which  the 
milk  may  be  seen,  and  this  is  again  connected  with  a  small  rubber 
tube.  T$y  means  of  a  spigot  in  the  tube  the  suction  may  be  cut  off 
when  the  teat  is  empty.  The  milk  is  conveyed  from  the  spigot  to  the 
head  where  the  milk  from  all  four  teats  unites  and  passes  into  the  large 
hose  which  carries  it  to  the  pail. 

This  machine  has  been  in  operation  since  1892. 

A    POWER    MILKER. 

The  accompanying  illustration  (pi.  2)  shows  a  cow  milker  which 
has  recently  been  put  upon  the  market.  It  consists  of  an  ordinary" 
milk  pail  made  of  block  tin  and  holding  about  15  quarts.  On  top  of 
this  pail  is  a  tight-fitting  lid  of  aluminum.  On  this  lid  is  mounted  a 
pump  or  pulsator  which  works  automatically  and  causes  the  intermit- 
tent action  of  the  machine.  Connections  are  made  by  means  of  rubber 
tubing  to  the  exhaust  and  air-pressure  pipes,  which  are  laid  thru  the 
stable  with  convenient  branches  between  the  cows.  Two  rubber  tubes, 
each  about  3  feet  long,  are  also  connected  with  convenient  nozzles  on 
the  lid,  and  on  the  other  end  of  each  are  -4  cups  which  fit  snugly  over 
the  cow's  teats,  2  cows  being  milked  into  one  pail.  As  the  pulsator 
oscillates  (at  the  rate  of  about  60  times  a  minute)  the  vacuum  is  alter- 
nately' turned  on  and  off,  the  teat  cups  causing  suction  and  release  at 
each  alternate  stroke. 

The  machinery  for  operating  the  pulsator  consists  of  an  exhaust 
pump  and  a  compressor;  the  exhaust  produces  the  suction  and  oper- 
ates the  pulsator  in  one  direction,  while  the  compressor  operates  the 
pulsator  in  the  opposite  direction. 


12          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 
A    MILKER    DESIGNED    FOR   EITHER   HAND   OR   POWER. 

The  milking  machine  shown  in  Plate  3  consists  of  a. simple  air  pump, 
composed  of  two  cylinders,  each  of  which  is  independent  of  the  other 
in  its  action.  One  cylinder  milks  one  cow,  and  one  the  other.  The 
valve  chambers,  supported  at  the  ends  of  the  rods,  are  for  the  purpose 
of  keeping  the  milk  from  running  back  into  the  pump,  and  also  to  give 
the  pump  sufficient  and  continued  suction  for  the  space  of  about  ten 
to  fifteen  seconds.  When  the  pressure  is  off  of  one  of  these  valve 
chambers  the  milk  flows  from  it  of  its  own  gravity  into  the  pail. 
Each  cow  can  be  milked  separately,  or  both  can  be  milked  into  one 
pail,  as  desired.  Cows  can  be  milked  into  either  open  or  closed  pails. 
The  machine  is  operated  by  either  hand  or  po\ver,  the  hand  machine 
being  convertible  into  a  power  machine  by  simply  bolting  an  air  device 
to  it.  In  the  operation  of  the  power  machine  it  is  necessary  to  pipe 
the  stables,  a  comprest  air  tank  being  required,  which  must  be  filled 
by  some  power  running  an  air  compressor.  There  are  no  pulsators 
or  vacuum  pumps  in  the  construction  of  the  machine.  The  teat  cups 
are  provided  with  a  rubber  sleeve. 

THE    MACHINE    USED   IN    THE    INVESTIGATION. 

With  this  machine  the  milk  is  drawn  by  intermittent  suction. 
The  suction  may  be  created  by  either  a  vacuum  pump  or  a  steam 
ejector.  Connected  with  the  vacuum  pump  is  a  vacuum  reservoir  and 
a  pipe  running  the  whole  length  of  the  cow  stable,  with  a  connection 
valve  or  vacuum  cock  between  each  pair  of  cows.  A  safety  valve  is 
connected  to  the  reservoir  to  prevent  the  vacuum  from  running  higher 
than  is  desired. 

The  machine  itself  (pi.  4,  fig.  1)  consists  cf  a  heavy  tin  pail,  which 
is  cone-shaped  and  holds  about  55  pounds  of  milk.  The  cover  of  this 
pail  is  a  disk,  in  which  is  a  vacuum  motor  which  produces  the  pulsa- 
tions in  drawing  the  milk  from  the  teats.  The  cover  fits  the  pail 
tightly  and  excludes  all  air. 

To  operate  the  machine  it  is  placed  between  the  pair  of  cows  to  be 
milked.  A  rubber  tube  connects  the  pail  top  or  pulsator  with  the 
vacuum  cock  above  the  stanchions.  On  opening  the  cock  the  air  is 
drawn  from  the  pail  and  the  motor  immediately  starts.  The  degree 
of  pressure  maintained  is  about  one-half  atmosphere,  or  7^  pounds  to 
the  square  inch.  Leading  from  the  pail  cover  or  pulsator  are  two 
flexible  tubes  besides  the  one  leading  to  the  vacuum  cock  above  the 
stanchions.  At  the  end  of  each  tube  are  4  cups,  which  are  fitted  over 
the  teats  of  the  cow.  The  milk  from  the  '2  cows  is  discharged  into 
one  pail  (pi.  -i.  fig.  2).  In  operation  the  machine  makes  a  low,  click- 
ing sound,  which  is  caused  by  the  motor.  The  vacuum  pulsations  run 
from  50  -to  T<>  per  minute  and  may  be  easily  adjusted  to  the  speed 


BUL.  No.  92,  B.  A.  I. 


PLATE  1 


FIG.  1.— A  FOOT-POWER  Cow  MILKER  WITH 
ATTACHMENTS. 


FIG.  2.— THE  SAME  MACHINE  IN  OPERATION. 


?UL.   No.  92,  B.  A.   I. 


PLATE  2. 


FIG.  1 .— A  POWER  MILKER  WITH  ATTACHMENTS. 


FIG.  2.— THE  SAME  MACHINE  IN  OPERATION. 


But.  No.  92.  B    A    !. 


PLATE  3. 


FIG.  1.— MILKING  MACHINE  DESIGNED  FOR  USE  WITH  EITHER 
HAND  OR  POWER. 


FIG.  2.— THE  SAME  MACHINE  IN  OPERATION. 


But.  No.  92,  B.  A.  I 


PLATE  4. 


FIG.  1.— MILKING  MACHINE  USED  IN  EXPERIMENTS. 


FIG.  2.— THE  SAME  MACHINE  IN  OPERATION. 


DIFFERENT    KINDS    OF    POWER.  18 

required.  The  milk  in  passing  from  the,  cow  to  the  pail  goes  thru  a 
glass  inspection  tube,  so  that  the  operator  may  watch  the  How.  When 
the  milk  ceases  to  flow  the  suction  is  turned  off  and  the  action  of  the 
machine  stops.  Four  different  sizes  of  teat  cups  are  provided,  so  that 
different  sizes  of  teats  may  be  fitted. 

COST  OF  EQUIPMENT  FOB  MACHINE  MILKING. 

At  the  present  time  the  equipment  required  to  milk  a  herd  of  40 
cows  with  the  machines  and  the  cost  of  the,  same  would  be  as  follows: 

1.  An  engine  or  some  power  with  which  to  drive  the  machine.     For  milking 

up  to  8  cows  at  a  time,  a  2-horsepower  gasoline  engine  may  be  used, 
costing SI  05.  00 

2.  A  vacuum  pump,  costing 75.  00 

3.  \  vacuum  lank,  like  a  tank  that  is  used  in  connection  with  ranges  or 

stoves  in  kitchens,  costing 11.  00 

4.  The  piping  with  valves,  etc.,  necessary  in  barn,  depending  upon   extent 

of  plant,  number  of  cows,  etc.,  costing  for  a  42-cow  dairy  about 25.  00 

5.  Four  milking  machines,  costing 300.  00 


Total 516.  00 

One  machine  milks  2  cows  at  a  time,  and  it  has  been  found  practi- 
cable to  allow  one  machine  to  every  10  or  12  cows  when  equipping 
the  herd. 

In  a  general  way  it  m&y  be  said  that  the  entire  cost  of  installing  a 
plant  for  herds  of  different  sizes  would  be  about  as  follows: 

For  a  dairy  of  30  cows,  with  2  machines,  milking  2  cows  each  or  4  cows  at 

one  time,  cost  per  cow $13.  00 

For  a  dairy  of  40  cows,  with  3  machines,  milking  (i  cows  at  one  time,  cost  per 
cow 12.  00 

For  a  dairy  of  60  cows,  with  4  machines,  milking  8  cows  at  one  time,  cost  per 

cow 1 0.  00 

For  a  dairy  of  75  cows,  with  5  machines,  milking  10  cows  at  one  time,  cost  per 

cow S.  50 

For  dairy  of  100  cows,  with  8  machines,  milking  16  cows  at  one  time,  requir- 
ing about  a  4-horsepower  engine  and  a  larger  pump,  cost  per  cow 10.  00 

One  good  careful  man  or  woman  can  operate  -i  machines  milking  8 
cows  simultaneous^,  and  an  additional  hand  can  not  only  carry  awjiy 
the  milk,  but  assist  in  manipulating  the  cows'  udders.  The  operating 
expense  of  the  machines  is  comparatively  small. 

DIFFERENT  KINDS  OF  POWER  WHICH  MAY  BE  UTILIZED. 

The  kind  of  power  employed  to  operate  cow  milkers  is  not  impor- 
tant provided  it  is  uniform  and  can  be  depended  upon. 

Dairymen  well  know  that,  in  the  case  of  hand  milking,  if  they  were 
to  stop  for  a  time  when  a  cow  was  partially  milked  and  then  begin 
again  and  finish  milking,  the  chances  are  that  there  would  not  only  be 


THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

a  decrease  in  yield,  but  the  milk  would  be  of  poorer  quality.  A  sim- 
ilar effect  is  produced  in  the  case  of  machine  milking-.  If  the  engine, 
or  whatever  power  is  employed  to  work  the  pumps,  stops  for  an}' 
cause  during  the  milking,  a  marked  decrease  in  the  yield  of  milk 
results. 

Gasoline  engines, — These  are  most  commonly  employed  for  power 
at  the  present  time. 

Electric  -motor*.  —  Some  farmers  located  near  cities  find  electricity 
the  most  convenient  power.  This  has  worked  successfully  on  two 
farms  at  least.  In  one  case  a  trolley  line  passes  near  the  barn  and  a 
wire  is  attached  to  the  main  trolley  wire  and  connected  with  a  1-horse- 
power  electric  motor  inside  of  the  building.  As  electric  roads  are 
now  being  rapidly  built  thru  country  districts  it  is  quite  possible  that 
this  may  prove  a  popular  method  of  securing  power  to  operate  cow 
milkers. 

8team  power. — Steam  engines  are  employed  on  some  farms,  and 
they  will  be  found  to  work  satisfactorily  in  supplying  power  to 
operate  the  milking  machines.  Where  steam  is  used  on  farms  for 
other  purposes  it  can  be  made  to  run  the  milkers  with  but  little  extra 
expense. 

EXPERIMENTS  IN  WHICH  HAND  AND  MACHINE  MILKING  WERE 

COMPARED. 

Two  experiments  were  conducted  by  the  Daily  Division  in  which 
tests  were  made  to  determine  the  time  required  to  milk  by  hand  and 
by  machine.  The  yield  of  milk,  its  chemical  composition,  and  other 
points  that  were  considered  of  interest  to  dairymen,  were  also  studied. 

EXPERIMENT   NO.  1. 

From  a  herd  of  13  cows,  8  were  selected  for  this  test,  the  others 
being  nearly  dry.  The  animals  were  Jerseys  and  Ilolsteins,  all  5 
years  old  or  over.  This  herd  had  been  milked  with -the  machines  for 
over  three  years. 

The  cows  were  divided  into  two  lots  of  -±  each  in  such  a  way  that 
eaclf  lot  gave  practically  the  same  amount  of  milk.  The  test  con- 
tinued for  thirty  days  and  was  divided  into  three  periods  of  ten  days 
each.  At  the  beginning  of  the  first  period.  Lot  1  was  milked  by  hand 
and  Lot  II  by  machine.  At  the  end  of  each  period  of.  ten  days  the 
methods  of  milking  the  two  lots  of  cows  were  reversed  so  that,  the 
results  from  milking1  by  the  two  methods  could  be  compared.  The 
milking  was  all  performed  by  one  man. 


HAND    AND    MACHINE    MILKING    COMPARED. 


15 


TABLE  1. — Machine  milking:  Time  required  to  milk,  and  yield  of  milk  and  strippings. 


The  cows  and  date. 

Morning. 

Evening. 

Total  for  day. 

Time  required. 

Yield  of  milk. 

Time  required. 

Yield  of  milk. 

Time  required. 

Yield  of  milk. 

j! 

Strippings. 

1 

H 

Machine 
milk. 

<jf 

'5. 
.£• 

03 

L!>s. 
1.50 

.80 
aS.10 
.50 
.50 
.50 
.60 
.  40 
.40 
.90 

2 

Machine 
milk. 

Strippings. 

Total  yield. 

LOT  II,  4  COWS. 

July  21... 

Min. 
14.00 
14.00 
14.00 
13.  50 
14.50 
13.00 
12.50 
13.00 
13.00 
12.00 

Lbs. 
30.50 
36.50 
31.50 
36.50 
35.00 
36.50 
34.00 
30.50 
38.00 
37.50 

I.b». 
1.25 

.50 
.75 
.50 
.50 
.  25 
ft  5.  25 
.75 
.50 

Lbs. 

31.75 
37.25 
32.00 
37.25 
35.50 
37.00 
34.25 
35.75 
38.75 
38.00 

Min. 
13.00 
12.00 
13.00 
15.00 
11.50 
12.50 
12.00 
14.00 
13.  50 
12.00 

Lbs. 
25.  00 
34.75 
28.00 
36.50 
35.00 
34.50 
32.00 
34.80 
32.00 
29.25 

Lbs. 
26.50 
35.55 
36.10 
37.00 
35.50 
35.00 
32.60 
35.  20 
32.  40 
30.15 

Min. 

27.00 
26.00 
27.00 
28.50 
26.00 
25.50 
24.50 
27.00 
26.50 
24.00 

1*8. 

55.50 
71.25 
69.50 
73.00 
70.00 
71.00 
66.00 
65.30 
70.00 
66.  75 

Lbs. 
2.75 
1.55 
8.60 
1.25 
1.00 
1.00 
.85 
5.  65 
1.15 
1.40 

Lbs. 
58.25 
72.80 
68.10 
74.25 
71.00 
72.00 
66.85 
70.95 
71.15 
68.15 

Julv  22 

Julv  23  

July  24  
July  25 

Julv  26  
Julv  27.. 

Julv  28  
Julv  29  
Julv  30. 

Total  
Daily  average  

LOT   I,  4   COWS. 

Julv  31 

133.50      346.50 
13.35;       34.65 

11.00 
1.10 

357.  50 
35.  75 

128.  50 
12.  85 

321.80 
32.18 

14.  20 
1.42 

336.00262.00     668.30 
33.60   26.20       66.83 

25.  20     693.  50 
2.  52       69.  35 

13.  00       30.  00 
13.50       34.50 
13.00       34.00 
12.  50       36.  00 
12.  00       32.  00 
13.00       34.50 
12.  50       32.  50 
13.00       33.00 
12.  50       33.  50 
13.00       34.25 

.75 
.75 
.50 
.50 
.75 
.75 
.75 
.50 
.50 
.50 

30.75   12.50   27.30 
35.25   14.00   27.30 
34.50   13.00,  27.00 
36.50   13.00   24.00 
32.75   13.00   24.  ,50 
35.25   15.00   26.25 
33.25.  14.00!  25.50 
33.50    14.00;  27.25 
34.00   15.  50i  27.75 
34.75;  13.00!  34.00 

1.80 
.50 
.50 
1.00 

i!oo 

.30 
.  75 
.  75 
.40 

29.10 
27.  80 
27.50 
25.  00 
25.  25 
27.  25 
25.  80 
28.00 
28.  50 
34.40 

25.  50 
27.50 
26.00 
25.50 
25.  00 
28.  00 
26.  50 
27.00 
28.00 
26.00 

57.30 
61.80 
61.00 
60.00 
56.50 
60.75 
58.00 
60.  25 
61.25 
68.  25 

2.  55 
1.25 

1.00 
1.50 
1.50 
1.75 
1.05 
1.25 
1.  25 
.90 

59.85 
63.05 
62.00 
61.50 
58.00 
62.  50 
59.  05 
61.50 
62.  50 
69.  15 

August  1          

August  '' 

August  3 

August  4  

August  5 

August  6  

August  7 

Augusts  
August  9  

Total  

128.00     334.25 
12.  80:       33.  42 

6.25 
.62 

340.  50  137.  00  270.  85 
34.05   13.70,  27.08 

7.  75  27S.  60  265.  00 
.77    27.86,  26.50 

605.  10 
60.  51 

14.00 
1.40 

619.  10 
61.91 

Daily  average  

LOT  II,  4  COWS. 

August  10             

11.00 
12.00 
13.50 
12.50 
13.00 
14.00 
13.00 
12.50 
13.50 
14.00 

36.00 
36.00 
33.00 
34.00 
40.00 
39.50 
35.50 
34.  50 
33.00 
40.00 

.50 
.25 
.50 
.25 

!Eo 

.25 
.  25 
.50 

36.50    11.25   30.10 
36.25    12.00   32.00 
33.50   15.  00  ''27.  75 
34.25   13.  00  ''31.  00 
40.25    16.00   26.00 
39.75^  16.50   33.50 
36.00    13.50;  31.00 
34.75    14.00   36.50 
33.25   14.50   40.00 
40.  50    16.  00  e37.  50 

1.00   31.10 
.25    32.25 
5.25    33.00 
3.75   34.75 
1.50    27.50 
.25   33.75 
.70   31.70 
.25   36.75 
.50    40.50 
5.  75   43.  25 

22.  25 
24.00 
28.  50 
25.  50 
29.  00 
30.  50 
26.  SO 
26.  .50 
28.  00 
30.00 

66.10 
68.00 
60.  75 
65.00 
66.00 
73.00 
66.50 
71.00 
73.00 
77.  .50 

1.50 
.50 
5.  75 
4.00 
1.75 
.50 
1.20 
.50 
.  75 
6.  25 

67.60 
68  50 
66.50 
69.00 
67.75 
73.50 
67.70 
71.  50 
73.  75 
83.  75 

August  11 

August  12  

August  13  

August  1  4 

August  15  

August  16  

August  17  

August  IS  . 

August  19 

Total  
Daily  average  

Grand  total  .. 
General  average  .  .. 

129.00     361.50 
12.90       36.15 

3.50 
.35 

365.00  141.75325.35 
36.50    14.17    32.53 

19.20344.55 
1.92    34.45 

270.  75     686.  85  22.  70      709.  50 
27.  07        tis.  6,s    2.  27        70.  95 

390.501,042.25 
13.02        34.71 

20.  75 
.69 

1,063.00407.25918.00 
35.43    13.57    30.60 

41.15959.15 
1.37    31.97 

797.  75  1,  960.  25  61.  90  2.  022.  10 
26.59       65.34   2.06       67.40 

a  One  oi 
&Onec( 
(•Black 
(I  Black 
e  Black 


lilk  (7.5  pounds)  on  account  of  stranger  being  in  barn, 
lilk  (5  pounds)  on  account  of  stranger  being  in  barn. 

milk  and  gave  4.75  pounds  by  hand. 

milk  and  gave  3  pounds  by  hand  (stranger  in  barn). 

milk  and  gave  5  pounds  by  hand. 


»          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 
TAKLE  2. — Hand  milk'tiiy:   Time  required  l<>  iitilk,  and  i/ield  of  milk  and  strappings. 


The  cows  nnd 
date. 

Morning. 

Evening. 

Total  for  day. 

•c            Yield  of  milk. 

Time  required. 

Yield  of  milk. 

•5                 Yield  of  milk. 

'=         ?        I 

~ 

| 

tb 

'£. 

'C 

y. 

c 

'§_                  -5 

7             "3 

Stripping*. 

~ 

LOT  1.  4  COWS. 

lv  •'! 

V/»      7./i.-.     /./is 

/  /IS 

Win 

//IS 

Us 

/6s 

ttis. 
3.300 
2.  500 
2.700 
2.500 
2.  .500 
2.  .500 
2.250 
2.000 
2.600 
3.650 

/As. 
66.  500 
67.  700 
64.900 
67.500 
67.25"' 
72.500 
66.  250 
70.000 
71.400 
66.150 

21.00   31  00      J  50 

32.50 
37.  50 
35  00 

20.00 
16.00 
17  00 

32.  20 
29.  20 
°8  ''0 

1.80 

1  .  00 
1  70 

34.00 
30.  20 
•"»  90 

41.000       63.20 
38.  000       65.  20 
3«.  500       62.  20 
37.  000       65.  00 
45.  000       (',4.  75 
36.  .500       70.  00 
37.  500       64.  00 
41.2.50       68.00 
38.  500       68.  80 
37.  000       62.  50 

.     Iv"1' 

22.00   36.0H      1.50 
21.50   34  00      1  00 

1  v  •>:? 

.     1  v  2  1  

21.00   32.00      1.25 
24.50   35.00     1.25 
19.50   35.50      1.00 
18.59   32.00      1.25 
24.  (X)   35.00      1.00 
20.00   35.00      1.50 
21   (Hi    3"  50      1   75 

33.  25 
36.25 
36.50 
33.  25 
36.  00 
36.  5( 
34  '-"5 

16.00 
20.51 
17.  00 
19.  CK 
17.25 
18.  50 
16  00 

3  !.  00 
29.  75 
31.51 
32.  00 
33.  00 
33.  80 
30  00 

1.25 
1  .  25 
1  .  50 
1.  IX 
1.00 
1.  H 
1   90 

34.25 
31.00 
36.  00 
33.00 
34.  01 
34.90 
31  90 

.     Iy25  
.     Iy26  
.     lv  "7  

,ll  lv  29  

Ji  lv  30 

Total  

213.00338.  00   13.  CO 
21.30   33.80     1.30 

351.00177.25 
35.10    17.72 

315.65 
31.56 

13.50329.15 
1.35   32.91 

390.  250     653.  65 
39.  025       65.  36 

26.  500 
2.  650 

680.  150 
•     68.  015 

Daily  n  \vrasre.. 

LOT  II.  4  ( HWS 


26.00  S7.00        .75 

25.  .50  31.00        .75 

21.50  34.00        .75 

23.  00  26.  00  a  7.  50 

23.50  31.00        .75 

21.00  36.00        .  75 

24.00  31.50 

22.00  35.00 

23.00  36.  50 

21.00  36.00 


47.  000 
45.  500 
40.  500 
44.000 
43.  500 
43. 500 
43.  000 
45.  000 
44.. 500 
43.1100 


63. 850 
6^.500 
65. 900 
66.  800 
7u.  000 
63. 500 
67. 200 
71.950 
70. 400 


Total 

Daily  average 


133.  50334.00    13.2" 


3!7.2.>20i;.  On:;21.65 


31.75.  19.00  24.00 

29.00  20.00  25.25 
31.25  16.00  2v  50 
33.25  H.i.  UO  26.25 
32.50  l;l.0:i  29.00 

31.1  0  16.00  'JS.-J 
31.75  IS.  00  29.  0 
31.75  17.00  32.0 
33.25  IV  00  31.5 


43.000 
41.000 
37.000 
10.000 
39.000 
37.0011 
39.000 
37.  ( 00 
oiio 


1 .  550 
1.600 
2.500 
1.250 

1 .  750 

2.  500 
2.  000 
2.000 


Total..      ...  210.00307.00 


186. 45   20.150     606.600 


Grand  ti  itnl .  i;56.  50  979.  Oi 


33.76   18.71    30.66     1.15   31.81 


HAND    AND    MACHINE    MILKING    COMPARED.  17 

TIME   KEQUIRED    FOR    HAND    AND    MACHINE    MILKING    COMPARED. 

Naturally  one  of  the  first  questions  asked  when  a  dairyman  is  con- 
sidering the  installation  of  milking  machines  is:  How  much  time  will 
be  saved  by  their  use?  In  the  experiment  outlined  above  one  man 
performed  the  milking-,  1  cow  milker  being  used  in  case  of  the  lots 
milked  by  machinery.  The  machine  was  operated  by  a  1-horsepower 
electric  motor.  By  referring  to  Tables  1  and  2  the  reader  can  readily 
compare  from  da}7  to  day  the  time  required  to  milk  by  the  two  methods. 
A  glance  at  the  general  averages  for  thirty  days  shows  that  the 
average  time  required  for  one  man  to  milk  4  cows  with  the  machine 
was  13.02  minutes  in  the  morning  and  13.57  minutes  in  the  evening, 
or  a  total  of  26.50  minutes  for  the  day.  These  figures  include  the 
time  used  in  putting  the  machine  in  place  and  adjusting  the  teat  cups,, 
about  one-fourth  minute  per  cow  being  required  to  adjust  them 
properl}T. 

In  considering  the  time,  the  amount  of  milk  secured  should  also  I  e 
considered.  Other  things  being  equal,  cows  producing  a  large  amount 
of  milk  require  the  most  time  to  perform  the  milking.  In  case  of  the 
4:  cows  milked  by  hand  it  will  be  noted  that  it  took  an  average  of 
21.88  minutes  to  milk  them  in  the  morning  and  18.71  minutes  in  the 
evening,  or  a  total  of  40.50  minutes  for  the  day.  There  was  therefore 
a  daily  saving  of  3.5  minutes  per  cow.  or  14  minutes  on  4  cows,  thru 
the  use  of  the  machines. 

It  should  be  noted,  however,  that  the  time  saved  by  the  employment 
of  machines  was  not  the  result  of  greater  speed  in  milking,  but  in  the 
operator's  ability  to  milk  2  cows  at  once.  Indeed,  one  man  can  look 
after  5  machines  milking  10  cows  at  once,  thus  greatly  increasing  this 
saving  of  time.  (See  experiment  No.  2.) 

Speed  of  the  machine. — As  stated  in  the  description,  the  pulsator 
can  be  adjusted  so  that  the  action  will  be  fast  or  slow;  50  to  (>0  pulsa- 
tions per  minute  is  the  rate  usually  recommended.  The  more  rapid 
the  pulsations  the  faster  the  machine  will  milk,  up  to  a  certain  limit. 
The  writer  saw  one  cow,  giving  a  good  How.  milked  absolutely  clean 
with  a  machine  in  2^  minutes,  the  number  of  pulsations  being'  150  per 
minute.  It  is  believed,  however,  that  such  rapid  milking  for  any 
length  of  time  has  a  bad  influence  upon  the  cow  and  after  a  time  she 
might  object  to  the  machine  and  refuse  to  give  down  her  milk. 

Cows  vary  greatly  individually,  and  it  is  the  best  plan  to  adjust  the 
speed  of  the  machine  as  close I}T  as  possible  to  the  requirements  of  each 
cow.  Cows  with  short  teats  can  he  milked  with  the  machine  set  at 
greater  speed  than  cows  with  large,  long  teats.  The  ordinary  type  of 

lloL'2— No.  i»:>— U7 o 


18          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

Ayrshire  cow,  for  example,  can  probably  be  milked  by  more  rapid  pul- 
sations than  the  Holstein.  Those  acquainted  with  milking-  these  two 
types  of  cows  by  hand  know  this  to  be  true,  and  that  in  milking  some 
cows  the  milk  is  ready  to  be  drawn  as  fast  as  the  milker  can  manipu- 
late the  teats. 

While  the  machines  were  in  operation  the  attendants  massaged  the 
udders  of  the  cows  and  watched  to  see  that  they  were  milking  freelv. 
Care  was  taken  to  treat  the  animals  as  nearly  as  possible  the  same  at 
each  milking,  so  they  would  become  accustomed  to  the  machines. 

YIELD    OF    MILK    FROM    HANI)    AND    MACHINE    MILKING    COMPARED. 

The  yield  of  milk  is  perhaps  the  most  important  matter  to  the  dairy- 
man. Any  method  of  milking  that  has  a  tendency  to  decrease  the  flow 
to  am-  appreciable  extent  can  hardly  be  considered  practicable.  This 
point  was  studied  for  a  period  of  thirty  days  in  this  experiment  with 
the  milking  machine.  While  a  much  longer  period  is  necessary  to 
settle  this  question,  the  results  secured  indicate  at  least  what  may  be 
expected  when  the  machines  are  properly  handled.  In  this  test  the 
cows  were  carefully  handled,  care  being  taken  to  adjust  the  teat  cups 
to  suit  the  individuality  of  each  cow,  also  to  use  cups  of  the  same  size 
on  each  cow  every  time. 

As  already  stated,  two  lots  of  cows  were  selected  that  yielded  prac- 
tically the  same  amount  of  milk.  Keferring  to  Tables  1  and  '"1  it  will 
be  noted  that  the  total  yield  of  milk  for  4  cows  during  thirty  days  was 
1.898.75  pounds  from  hand  milking"  and  1,960.^5  pounds  from  machine 
milking/'  not  including  strippings — a  difference  of  t!1.5  pounds,  or 
3.24  per  cent,  in  favor  of  the  machine.  A  study  of  the  yields  of  the 
different  lots  of  cows  ror  the  different  periods  shows  that  Lot  I.  which 
started  with  hand  milking,  gradually  decreased  in  milk  flow  when 
changed  to  the  machines  and  also  continued  to  decrease  when  changed 
again  to  hand  milking.  The  yields  of  Lot  II.  which  began  with 
machine  milking,  show  that  these  cows  decreased  when  changed  to 
hand  milking  and  materially  increased  in  yield  when  changed  back 
again  to  machine  milking. 

"One  cow  held  up  part  of  her  milk  <me  day  (see  Table  L'i. 

&One  cow  held  up  a  small  quantity  of  milk  a  few  times  and  was  linished  by  hand 
(see  Table  I). 


HAND    AND    MACHINK    MILKING    COMPARP^D.  19 

The  yields  of  Lots  I  and  II  for  the  three  10-day  periods  were  as 
follows: 

Yields  from  machine  milking  and  hand  milking  compared. 

Lot  I,  4  cows:  Pounds. 

First  10-day  period,  cows  milked  by  hand 653.  (55 

Second  10-day  period,  cows  milked  by  machine 605.  10 

Third  10-day  period,  cows  milked  by  hand 586.  45 

Lot  II,  4  cows: 

First  10-day  period,  cows  milked  by  machine 668.  30 

Second  10-day  period,  cows  milked  by  hand 65K  65 

Third  10-day  period,  cows  milked  by  machine 686.  85 

As  the  cows  of  Lot  II  increased  in  yield  when  changed  back  again 
to  machine  milking  in  the  third  period,  when  the  natural  tendency 
was  to  decrease  owing  to  advance  in  lactation,  it  appears  that  the 
machine  had  a  favorable  influence  upon  the  production  of  this  lot  of 
cows. 

As  Lot  1  was  used  during  two  periods  of  the  hand-milking  test  and 
in  only  one  period  with  the  machine  test,  and  Lot  II  the  reverse,  a 
fairer  comparison  may  be  drawn  by  averaging  the  yields  where  the 
same  lot  of  cows  was  used  twice  in  either  test.  The  result  of  this 
method  of  comparison  is  shown  in  the  tabulation  which  follows: 

Comparison  of  the  milk  yield  of  the  two  lots  of  cows  (not  including  stripping*). 

Hand  milking:  Founds. 

Lot  I,  average  of  first  and  third  periods 620.  05 

Lot  II,  second  period 658.  65 


Total 1,  278.  70 


Machine  milking: 

Lot  1 1 ,  average  of  first  and  third  periods 677.  50 

Lot  I,  second  period 605.  10 


Total 1,  282.  60 

It  appears  that  the  yield  of  milk,  not  including  strippings,  amounted 
to  1/2TS.T  pounds  from  hand  milking  and  1._?<S2J>  from  machine  milk- 
ing, a  difference  of  3.9  pounds  also  in  favor  of  the  machine.  This 
further  comparison  will  serve  to  strengthen  the  conclusion  already 
given  that  when  the  machines  are  properly  handled  and  carefully 
adjusted  to  suit  the  needs  of  individual  cows  the  yield  of  milk  com- 
pares favorably  with  that  of  hand  milking. 


20          TTTK    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

THOKONKHH    OF    HANI)    AND    MACHINE    MILKING    COMPARED. 

A  machine  that  does  not  milk  cows  clean,  or  at  least  as  clean  as  the 
average  farm  hand  does,  is  of  but  little  service  to  dairymen.  This 
point  was  tested  as  thoroly  as  possible  in  the  experiment  just  described. 
The  man  who  milked  the  cows  by  hand  in  this  experiment  was 
instructed  to  milk  the  cows  as  normally  as  possible  and  not  to  go  to 
extremes  in  either  direction.  It  is  believed  that  a  fair  trial  was  made 
in  this  respect. 

Keferring  to  Table  1  it  will  be  observed  that  the  amount  of  strip- 
pings  was  fairly  uniform  from  day  to  day  in  case  of  both  hand  and 
machine  milking.  A  comparison  of  the  amount  of  strippings  from 
each  lot  of  cows  for  the  three  10-day  periods  is  shown  in  the  following 
tabulation: 

Comparison  of  amount  of  strippings  in  hand  and  machine  milkintj. 

Hand  milking:  Pounds. 

Lot  I,  first  period 2<>.  50 

Lot  I I,  second  period 21 .  70 

Lot  I,  third  period 20.  1 5 


Total..  .  68.85 


Machine  milking: 

Lot  II,  first  period 25.  20 

Lot  I,  second  period 14.  00 

Lot  II,  third  period 22.  70 


Total 61 .  90 

The  total  strippings  from  hand  milking  for  the  -i  cows  for  thirty 
days  is  shown  to  be  68.35  pounds,  and  from  machine  milking  <>L.i«) 
pounds,  or  6.15  pounds  less  for  the  machine.  The  average  strippings 
per  cow  for  each  milking  was  -L55  ounces  by  hand  and  4.12  ounces  by 
machine. 

The  composition  of  the  milk  was  not  determined  in  this  experiment. 

EXPERIMENT    NO.   2. 

This  experiment  was  conducted  with  20  cows  selected  from  a  herd 
of  65.  All  kinds  of  cows  were  selected  for  the  test,  including  hard 
and  easy  milkers,  heifers,  and  mature  animals,  and  fresh  cows  as  well 
as  those  advanced  in  lactation;  also  including  cows  of  nervous  temper- 
ament which  it  was  known  did  not  take  kindly  to  the  machine.  This 
•vvas  done  in  order  that  a  thoro  study  might  be  made.  The  20  cows 
were  divided  into  two  lots  of  10  each,  which  we  will  designate  as  Lots 
land  II. 


HAND    AND    MACHINE    MILKING    COMPARED.  21 

Lot  I  was  milked  by  hand  and  Lot  II  by  machine  for  a  period  of  10 
days;  the  methods  of  milking  were  then  reversed  and  Lot  I  was  milked 
by  machine  and  Lot  II  by  hand,  2  days  being  allowed  between  the 
periods  to  make  the  change.  Five  machines  were  used  to  milk  the 
10  cows.  These  were  handled  by  one  man.  One  man  also  milked 
the  10  cows  by  hand  the  greater  part  of  the  time.  Whenever  more 
than  one  man  was  employed  the  results  were  put  on  the  basis  of  one 
man;  that  is,  if  two  men  milked  the  10  cows  in  40  minutes  this  was 
considered  equivalent  to  one  man  milking  80  minutes.  This  exper- 
iment differed  from  the  one  previously  described  in  that  more  cows 
were  included  and  less  attempt  was  made  to  adjust  the  teat  cups  to  the 
different  cows  or  to  use  the  same  machine  on  the  same  pair  of  cows 
every  time,  this  matter  being  left  largely  to  the  dairyman  in  charge. 
These  points  will  be  considered  in  studying  the  results. 


22          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 


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24          THE    MILKING    MAOHTNK    AS     A    FACTOR    IN    DAIRYING. 

TIME    KEQUIRED    FOR    HAND    AND    MACHINE    MILKING    COMPARED. 

The  accompanying  table  shows  the  time  required  to  milk  the  cows 
by  the  two  methods  during  the  different  periods.  In  this  experiment 
one  man  handled  5  machines  with  little  difficulty.  The  man  who 
milked  the  cows  by  hand  was  unusually  thoro  and  took  somewhat  more 
timo  to  do  the  work  than  the  average  milker. 

It  will  be  noted  that  the  average  time  required  for  one  man  to  milk 
the  10  cows  with  the  machines  for  20  days  was  19.4  minutes  in  the 
morning  and  17.67  minutes  in  the  evening,  or  a  total  of  37.07  minutes 
for  the  day.  The  time  stated  includes  the  time  required  for  putting 
the  machines  in  place,  adjusting  the  teat  cups,  and  milking;  the  aver- 
age time  per  cow  being  1.04  minutes  in  the  morning  and  1.76  minutes 
in  the  evening,  or  a  total  of  3.7  minutes  for  the  day. 

In  the  case  of  the  10  cows  milked  by  hand  it  will  be  noted  that  it 
required  for  the  20  days  an  average  of  81  minutes  in  the  morning  and 
73.9  minutes  in  the  evening,  or  a  total  for  the  day  of  154.9.  The 
average  time  required  per  cow  was  therefore  8.1  minutes  in  the  morn- 
ing and  7.39  minutes  in  the  evening,  or  a  total  of  15.49  minutes  for 
the  day.  On  the  basis  of  these  results  the  daily  saving  per  cow  thru 
the  use  of  the  machines  amounted  to  11.79  minutes,  or  117.!)  minutes 
for  the  10  cows.  Carrying  the  comparison  still  further,  the  saving 
for  60  cows  (the  number  in  this  herd)  would  amount  to  11.7  hours  per 
day  if  one  man  performed  all  of  the  work,  which  of  course  would  not 
be  possible  for  a  herd  of  this  size,  altho  the  writer  has  known  one  man 
to  milk  60  cows  with  6  machines  on  more  than  one  occasion,  the  time 
required  being  about  2  hours.  If,  however,  we  include  the  time  of 
the  man  who  removed  the  milk  and  assisted  in  manipulating  the  cow's 
udders  the  saving  of  time  is  reduced  to  one-half,  or  58.45  minutes  per 
day  for  the  10  cows.  These  figures  furnish  sufficient  proof  for  the 
statement  that  the  machines  are  t;time  savers.'7 

YIELD    OF    MILK    FROM    HANI)    AND    MACHINE    MILKING    COMPARED. 

As  previously  stated,  but  little  attention  was  given  to  properly 
adjusting  the  machines  by  the  attendants  in  this  herd.  Further  than 
this,  it  was  known  that  1  or  2  of  the  cows  selected  did  not  take  kindly 
to  the  machine,  but  it  was  desired  to  have  the  cows  in  the  test  represent 
the  average  of  the  herd.  While  a  longer  period  than  20  days  would 
have  been  desirable,  the  results  indicate,  at  least,  what  may  be  expected 
under  the  conditions  which  prevailed  during  this  test. 

Referring  to  Table  3,  it  will  be  observed  that  the  total  yield  of  milk 
for  10  cows  during  the  20  days,  was  4,371  pounds  from  hand  milking 
and  4.062.5  pounds  from  machine  milking,  not  including  strippings — a 
difference  of  308.5  pounds,  or  7.59  per  cent,  in  favor  of  hand  milking. 


HAND    AND    MACHINE    MILKING    COMPARED.  25 

This  result  is  not  surprising  when  we  consider  the  careless  manner 
in  which  the  machines  were  adjusted  to  the  animals,  and  that  this  fre- 
quently resulted  in  the  animals  holding  up  their  milk.  Further,  the 
fact  should  be  noted  that  the  hand  milker  in  this  instance  was  unusu- 
ally careful,  taking  an  average  of  7.75  minutes  to  milk  a  cow  at  each 
milking. 

The  results  tend  to  show  that  where  milking  machines  arc  used 
carelessly  they  are  a  disadvantage  to  the  dairyman  from  the  standpoint 
of  yield.  The  same  holds  true  of  other  machinery  on  the  farm;  the 
more  complex  it  is  the  more  care  and  skill  is  required  to  secure  the 
best  results;  but  with  skill  and  care  the  more  machinery  the  better, 
up  to  a  certain  limit.  This  is  brought  out  in  experiment  No.  1,  where 
the  milking  machine  held  its  own  or  showed  an  advantage  at  every 
point. 

THORONESS    OF    HANI)    AND    MACHINE    MILKINO    COMPARED. 

As  previously  stated,  the  man  who  did  the  milking  in  this  experi- 
ment was  an  unusually  thoro  milker  and  consequently  took  more  time 
for  milking  than  the  average  milker.  While  possibly  it  would  have 
been  better  to  have  employed  an  average  milker  in  this  experiment  in 
order  to  make  a  fair  comparison,  the  question  as  to  whether  the  milk- 
ing was  thoro  by  both  methods  can  be  made  clear.  In  a  few  instances 
1  or  2  cows  refused  to  give  clown  part  of  their  milk  (probably  owing 
to  the  teat  cups  not  being  of  the  proper  size).  This  of  course  increased 
the  amount  classed  as  strippings.  A  comparison  of  the  amount  of 
stripping^  (including  the  amount  held  up  by  the  machine-milked  cows, 
as  explained  above)  from  each  lot  of  cows  for  the  10-day  periods  is  as 
follows: 


Hand  milking:  Founds. 

Lot  I ,  first  period 30.  50 

Lot  II,  second  period 37.  50 


Total  . .  .   08.  00 


Machine  milking: 

Lot  II.  first  period 47.00 

Lot  I,  second  period 3S.  20 


Total So.  i'(> 

The  total  strippings  from  the  hand  and  machine  milking  for  the  1<> 
cows  during  '20  days  is  thus  shown  to  be  OS  pounds  and  So. 2  pounds. 
respectively.  On  this  basis  the  average  strippings  per  cow  at  each 
milking  amounted  to  '2.7  ounces  by  hand  and  3.4  ounces  by  machine. 
In  either  case  the  results  show  unusually  clean  milking. 
11522— No.  i»2— ii7 4 


'2<  THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

QUALITY    OK    THE    MIJ.K. 

Percentage  of  butter  Jut  in  milk. — A  sample  of  the  mixt  milk  was 
taken  at  eveiy  milking-  in  experiment  No.  2  and  tested  for  percentage 
of  fat  by  the  Babcock  method.  The  results  of  the  daily  tests  are 
shown  in  Table  3  and  the  average  for  the  different  periods  has  been 
brought  together  for  ready  comparison  in  the  following  tabulation: 

Percentage  of  butter /at  In  milk  <lr<(n-n  lnj  Imml  and  by  ni'irhine. 

Hand  milking:  Percent. 

Lot  I,  first  period  (10  days) 3.  82 

Lot  II,  second  period  (10  days ) 3.  72 


A  verage .   3.77 


Machine  milking: 

Lot  II,  first  period  (  10  days  i :-}.  37 

Lot  I,  second  period  ( 10  days) 3.  60 


Average 3.  41» 

It  will  be  noted  that  the  average  percentage  of  fat  in  the  milk  drawn 
by  hand  for  the  twenty  days  was  3.77  and  in  the  milk  drawn  by  machine 
o.41».  a  considerable  difference  in  favor  of  the  hand  milking. 

A  calculation  of  the  yield  of  butter  from  the  4,431*  pounds  of  milk 
resulting  from  the  hand  milking  (Table  3).  with  an  average  of  3.77 
per  cent  of  butter  fat.  gives  about  195.25  pounds  of  butter.  The  same 
amount  of  milk  with  an  average  of  3.4!)  per  cent  of  butter  fat  would 
yield  about  lso.75  pounds  of  butter,  or  14. 5<)  pounds  less  owing  to  the 
lower  percentage  of  butter  fat  presumably  resulting  from  the  use  of  the 
machines.  If  the  yield  of  butter  be  calculated  from  the  4.147.7  pounds 
of  milk  resulting  from  machine  milking,  with  an  average  of  3. 41)  percent 
of  fat.  it  will  be  found  to  be  about  1C)'.)  pounds.  Thus,  if  we  allow  for 
both  the  lower  yield  and  the  lower  percentage  of  fat  in  the  milk  in  this 
experiment,  the  balance  against  the  machine  with  1«  cows  for  twentv 
days  would  be  about  2<>  pounds  of  butter,  or  about  13  per  cent.  This 
appears  to  be  quite  an  unfavorable  showing  for  the  machine,  but  further 
experiments  are  necessary  to  determine  the  effect  of  machine  milking 
on  the  composition  of  milk,  as  it  is  always  unsafe  to  base  general  con- 
clusions on  the  results  of  a  single  experiment. 

J^/'C'-nt/ii//'  of  Ndlirfx  not  fiii." — The  percentage  of  solids  not  fat  was 
determined  by  means  of  the  lactometer.  Tests  were  made  from  samples 
taken  both  morning  and  evening.  The  detailed  results  are  given  in 
Table  3.  but  in  order  to  make  a  more  ready  comparison  only  the  aver- 
ages are  presented  here. 

"These  tests  were  made  bv  Prof.  W.  A.  Stocking. 


EFFECTS    OF    MACHINES    UPON    COWS.  27 

Percentage  of  solids  not  fat  in  milk  drawn  by  hand  and  by  machine. 

Hand  milking::  Percent. 

Lot  I,  first  period  ( 10  days) 8.  58 

Lot  II,  second  period  (10  days) 8.  46 

Average 8.  52 


Machine  milking: 

Lot  II,  ri rst  period  ( 10  days ) 8.  55 

Lot  I,  second  period  ( 10  days ) 8.  59 

Average 8.  57 

The  tinal  averages  shown  above  for  the  .solids  not  fat  are  very  close, 
being  8.52  and  8. 57,  respectively,  for  the  hand  and  machine  milk. 
While  further  study  should  be  made  on  this  point,  the  figures  secured 
indicate  that  there  is  practically  no  difference  in  the  amount  of  solids 
not  fat  between  machine  and  hand  drawn  milk. 

GENERAL,  CONSIDERATIONS. 
EFFECTS    OF    MILKING    MACHINES    UPON    THE    COWS. 

First  time  machine  is  used. — It  is  of  interest  to  note  how  the  milk- 
ing machine  affects  a  herd  of  cows  the  first  time  it  is  used.  The  writer 
was  present  in  a  barn  of  about  -io  cows  on  one  occasion  the  first  time 
the  machines  were  put  in  operation.  Some  of  the  animals  were  a  little 
restless  at  first,  owing  to  the  sight  of  the  machines  and  the  clicking 
of  the  pulsators,  but  soon  they  became  quiet  and  reconciled  to  their 
action.  One  feature  which  is  perhaps  a  little  surprising  is  that  heifers 
took  to  the  machines  as  readily  as  the  older  cows.  Only  one  cow  in 
the  herd  in  question  made  any  disturbance  at  all  while  the  machines 
were  being  attached,  and  this  was  due  principally  to  attaching  the 
machine  on  tin1  opposite  side  from  that  on  which  the  cow  had  been 
accustomed  to  be  milked  by  hand.  This  cow.  however,  soon  became 
quiet.  The  majority  of  the  cows  appeared  to  like  the  machines,  and 
stood  quietly  chewing  their  cuds  without  manifesting  any  discomfort. 
A  careful  examination  was  made  of  the  cows'  teats  and  udders  in 
several  dairies  where  the  machines  had  been  in  operation  for  several 
months  (in  one  case  over  three  years),  and  no  ill  effects  were  discovered. 

Nervous  <'<>/r*. — On  two  or  three  occasions  it  was  observed  that  when 
strangers  came  into  the  barn  during  milking  time  a  cow  would  appear 
frightened  and  refuse  to  give  down  all  of  her  milk.  This  occurred 
with  cows  being  milked  either  by  hand  or  by  machine.  When  the 
machines  are  properly  adjusted,  cows  of  a  nervous  disposition  do  not 
seem  to  resent  the  method. 

I\H-l\iiHj  ro//'\. — The  writer,  after  visiting  from  time  to  rim*1  several 
herds  where  the  machines  were  in  operation  and  observing  the  ma- 
chines working  continuously  in  one  lar<_n>  herd  fora  month,  failed  t<> 


28          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

find  any  cows  that  could  not  be  milked  because  of  the  "kicking" 
habit.  Reports  from  dairymen  who  have  had  experience  with  the 
machines  confirm  this  statement.  It  is  therefore  believed  that  the 
machines  give  less  trouble  with  such  animals  than  the  hand  method. 

Hard  in  ilker*. — The  hard  milker  and  the  cow  with  small  teats  are 
milked  much  more  easily  and  quickly  by  machine  than  by  hand,  and 
with  the  installation  of  milking  machines  there  will  be  less  reason  for 
disposing  of  such  cows.  With  the  hard  milker  it  is  simply  a  question 
of  keeping  the  machine  at  work  a  little  longer,  and  with  the  small- 
teated  cow  care  must  be  taken  to  have  the  teat  cups  of  the  proper  size, 
and  the  pulsations  may  also  be  a  little  more  rapid. 

JIe'tf<-rx. — The  results  already  secured  indicate  that  the  milking 
machine  is  particularly  well  adapted  to  heifers.  Since  milking  i.s  an 
artificial  process,  heifers  that  have  never  been  milked  by  hand,  as  a 
rule,  become  much  more  quickly  reconciled  to  the  machine  than  older 
animals  which  have  been  milked  for  years  by  hand.  The  latter  often 
have  their  udders  more  or  less  distorted  and  drawn  out  of  shape  by 
the  hand  method  and  do  not  as  readily  adapt  themselves  to  the  machine 
method. 

Coo.'*  tJ«it  refiixt  to  l>e  milked  v<tli  the  machine. — Occasionally  a  cow 
for  some  reason  refuses  to  give  down  either  a  part  or  all  of  her  milk. 
This  does  not  seem  to  be  due  to  nervous  temperament.  It  is  possible 
that  the  change  from  hand  to  machine  milking  is  too  radical  for  these 
particular  individuals  and  that  the}'  need  more  time  to  become  accus- 
tomed to  it.  Such  cows  do  not  make  any  objection  to  the  machines 
being  attached  to  them,  but  simply  stand  quietly  and  allow  the  machines 
to  pump  away  without  yielding  any  milk.  As  the  cows  that  give 
this  trouble  are  very  few  in  number,  dairymen  who  install  machines 
usually  dispose  of  them.  Frequently,  however,  cows  that  refuse  to 
give  their  milk  at  first  milk  freely  after  a  short  time. 

ADJUSTING    THE    MACHINES    TO    THE    COWS. 

Great  care  should  be  taken  to  see  that  the  proper-sized  teat  cups 
arc  used  for  each  cow.  Cows  with  large  teats  require  larger  and 
longer  cups.  If  the  cup  is  too  small  the  teat  will  wedge  into  it  and 
not  milk:  if  too  large  it  will  not  milk  properly  nor  stay  on  so  well. 
It  has  been  found  that  a  cow  requires  slightly  larger  cups  when  fresh 
than  she  does  when  advanced  in  the  period  of  lactation.  When  fresh 
the  udder  is  distended  and  a  very  small  portion  of  it  projects  into  the 
teat  cup.  Later,  the  udder  as  well  as  the  teats  are  softer  and  more 
limp  and  project  farther  into  the  cup.  During  the  tests  made  with 
the  machines  a  cow  occasionally  refused  to  give  down  her  milk  .simply 
because  the  teat  cup--  used  were  not  of  the  proper  size;  after  new  ones 
were  adjusted  the  cow  milked  out  clean.  This  emphasizes  the  impor- 
tance of  having  cow>  always  take  the  >ame  places  in  the  barn  and 


GENERAL    CONSIDERATIONS.  29 

using  teat  cups  of  the  same  si/e  at  each  milking.     Cows  will  then 
become  accustomed  to  the  cups  and  will  milk  clean. 

PRACTICABILITY    OF    USING     MACHINES    FOR    LARGE    A\D    SMALL    IIEKDS. 

^Naturally  the  largo  dairyman  will  be  the  first  to  adopt  the  cow  milker 
for  the  reason  that  his  equipment  will  cost  him  less  per  cow  than  the 
small  dairyman.  Again,  the  large  dairvman  has  more  at  stake  and 
has  to  depend  entirely  upon  the  hired  men  to  do  the  work.  If  they 
fail  him  the  work  falls  upon  himself  or  perhaps  upon  a  very  limited 
number  of  helpers.  With  the  installation  of  the  milking  machine  the 
large  dairyman  is  much  more  independent,  and  if  necessary  could  milk 
a  herd  of  5<>  cows  without  assistance.  This  would  be  next  to  impossi- 
ble without  it.  However,  there  seems  to  be  no  good  reason  why  a 
dairyman  with  a  herd  of  even  lo  or  12  cows  could  not  use  a  machine 
with  profit.  The  power  required  could  be  secured  at  small  cost,  and 
the  time  saved  could  be  used  to  advantage  in  working  the  team  longer 
on  the  farm  or  in  other  ways. 

HOW   THE    GENERAL    INTRODUCTION    OF    THE    MILKING   MACHINE    WTOULD 
AFFECT    THE    DAIRY    INDUSTRY. 

The  scarcity  of  milkers  and  the  unreliability  of  many  of  them  has 
had  a  tendency  to  keep  many  men  from  going  into  dairy  farming. 
Some  dairymen  who  have  been  in  the  business  have  been  obliged  to 
give  it  up  for  this  reason.  Great  interest  therefore  centers  around 
the  milking  machine,  especially  where  the  above  difficult}"  exists. 
With  the  introduction  of  the  milking  machine  only  about  one-half  the 
labor  will  be  required  to  milk  the  cows,  and  it  is  believed  that  the 
labor  employed  will  be  of  a  higher  class  than  heretofore  and  will  also 
command  higher  wages.  It  is  believed  also  that  the  advent  of  the 
milking  machine  will  have  a  tendency  among  farmers  who  now  have 
small  dairies  to  enlarge  their  plants  and  to  make  dairying  their  chief 
business.  The  trouble  has  been  in  the  past  that  too  many  farmers 
have  made  dairying  secondary  to  other  work,  and  when  anything  had 
to  l>e  neglected  it  was  always  the  dairy.  For  this  reason  the  profits  from 
their  dairies  have  boon  small.  Where  the  milking  machines  have  been 
introduced  they  have  influenced  dairymen  to  clean  up  their  burns  and 
take  more  pride  in  their  work.  This  naturally  will  result  in  the  pro- 
duction of  cleaner  milk  and  perhaps  in  some  cases  in  bettor  prices. 
Any  new  apparatus  which  has  a  tendency  to  improve  dairy  conditions 
should  be  welcomed  by  the  industry. 

SUGGESTIONS    FOR    IMPROVEMENTS. 

Improvements  will  doubtless  be  made  in  this  milking  machine  from 
time  to  time.  At  present  two  cows  are  milked  in  the  same  can.  thu- 
making  it  impossible  to  secure  the  weight  of  the  milk  from  >ii,-u'le 


30          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

cows.  A  great  deal  of  importance  is  now  being  placed  upon  records 
of  individual  cows  in  order  to  determine  whether  they  are  giving  a 
profit  to  their  owner,  and  this  is  a  movement  in  the  right  direction. 
If  individual  cans  were  provided  for  the  cows,  accurate  records  could 
)>e  secured  for  each  animal.  The  difficulty  of  making  machines  for 
individual  cows  is  not  insurmountable:  in  fact  a  few  machines  have 
already  been  built  which  keep  the  milk  from  the  two  cows  separate. 

Another  improvement  that  it  is  believed  would  add  much  to  the 
practicability  of  the  machine  is  a  teat  cup  that  could  readily  be  adjusted 
to  teats  of  any  size  or  shape.  At  present  cups  of  different  sizes  are 
used  to  meet  the  requirements  of  different  animals.  Some  improve- 
ments in  this  direction  are  already  in  progress. 

OBJECTIONS    AND    DIFFICULTIES. 

As  attention  has  been  called  to  the  advantages  to  be  secured  by  the 
use  of  milking  machines,  it  is  proper  to  point  out  some  of  the  objections 
and  possible  difficulties. 

Initial  outlay. — The  considerable  outlay  in  the  beginning  will  prove 
a  serious  obstacle  to  dairymen  of  limited  means;  and,  even  with  those 
who  are  financially  able  to  make  the  investment,  it  will  have  a  tendency 
to  deter  dairymen  from  the  installation  of  machines  until  their  practical 
utility  has  been  fully  demonstrated. 

Gardens  or  improper  uxe. — As  already  suggested,  the  machines  may 
be  improperly  or  carelessly  used.  The  operator  may  fail  to  select  and 
use  teat  cups  which  fit.  etc. 

Life  of  the  inachin'-. — The  machine  or  some  of  its  parts  may  prove 
short-lived,  thus  causing  expense  and  trouble. 

Troiil>l<ss  /r/'f/t  the  engine.— In  case  a  steam,  gasoline,  or  gas  engine  is 
used  (as  will  usually  be  the  case),  it  will  be  necessary  to  employ  some 
one  who  has  sufficient  knowledge  and  experience  to  run  the  engine. 
To  do  otherwise  is  to  court  disaster.  Even  with  such  a  man.  trouble 
with  the  engine  may  occur  any  day.  Besides,  the  use  of  an  engine  in 
or  near  the  barn  involves  danger  of  tire,  and  makes  extra  precautions 
necessary  to  avoid  invalidation  of  lire  insurance  on  the  building. 

Stnj^tigrx  «n<l  l>r<-nl'<l<>ir/,x. — In  the  operation  of  any  kind  of  ma- 
chinery there  is  always  danger  that  some  part  will  break  down  or  get 
out  of  order.  With  most  machinery  this  is  not  a  very  serious  obstacle, 
-hire  the  work  to  be  done  can  await  repairs.  But  milking  is  work 
that  can  not  be  postponed.  Attention  has  been  called  to  the  independ- 
ence of  the  dairyman  who  milks  with  machines  as  compared  with  the 
one  who  must  depend  on  hired  help  to  milk  his  cows  by  hand,  inas- 
much as  the  latter  may  find  himself  short  of  help  at  any  time.  The 
situation,  however,  is  re\ersed  when  the  engine  or  some  other  vital 
part  of  tin1  equipment  breaks  down  or  gets  seriously  out  of  order.  If 


NEED     FOR    FURTHER    INVESTIGATIONS.  31 

this  occurs  at  or  during  milking-  time  (as  is  likely),  the  dairyman  wtro 
has  installed  machines,  with  40  or  more  cows  to  milk,  will  find  it  very 
difficult,  if  not  impossible,  to  bring  in  milkers  enough  to  do  the  work 
by  hand;  and  the  difficulty  will  be  aggravated  if  he  loses  time  in  unsuc- 
cessful attempts  to  repair  the  machinery. 

Cleaning  and  care  of  the  inachin^. — As  this  matter  proper!}*  be- 
longs in  the  second  part  of  this  bulletin,  it  need  only  be  mentioned 
here  as  one  of  the  difficulties  which  will  demand  the  most  serious 
attention  of  the  dairyman  who  may  attempt  the  use  of  milking 
machines. 

NEED    FOR    FURTHER    INVESTIGATIONS. 

It  is  believed  that  the  present  investigations  have  yielded  much 
valuable  data,  but  they  have  been  too  limited  in  scope  and  time  to 
justify  final  positive  conclusions,  even  if  the  results  had  been  uniform 
in  their  indications.  The  fact  that  they  were  not  entirely  so  empha- 
sizes the  need  for  further  investigation. 

[r))Nf'ttl<-<!  questions. — Just  when  and  how  milk  is  formed  in  the 
udder  of  the  cow.  and  the  influences  favorable  or  unfavorable,  to  its 
formation,  are  subjects  which  are  not  well  understood.  Whether  a 
purely  mechanical  device  attached  to  the  cow's  teats  to  withdraw  the 
milk  from  her  udder  will  stimulate  and  favorably  influence  the  forma 
tion  of  milk  as  well  as  the  hands  of  the  living  milker  must  be  consid- 
ered an  unsettled  question. 

Yield  of  milk. — In  the  matter  of  yield,  experiment  No.  1  gave  a 
result  slight!}*  in  favor  of  the  machine,  while  experiment  ]So.  '2  gave 
a  result  slightly  unfavorable  to  it.  But  it  must  be  conceded  that  these 
experiments  were  too  limited  to  settle  definitely  the  question  of  yield 
even  for  short  periods,  while  the  effect  of  the  continuous  use  of 
machines  during  full  lactation  periods  was.  of  course,  not  tested  at  all. 

Co'm position  of  the  ruilk. — The  composition  of  the  milk  is  a  matter 
of  as  great  importance  as  the  yield,  and  the  effect  on  composition,  of 
the  means  and  methods  employed  in  milking,  is  a  part  of  the  unsettled 
problem  enunciated  above.  In  experiment  No.  I  the  composition  of 
the  milk  was.  unfortunately,  not  tested.  In  experiment  No.  '2  the 
milk  drawn  by  hand  showed  a  considerably  higher  percentage  of  butter 
fat  than  that  drawn  by  machines.  It  would  of  course  be  premature 
to  conclude  from  this  single  test  that  machine  milking  will  have  an 
unfavorable  influence  on  composition  of  the  milk,  but  the  need  for 
more  exhaustive  investigation  is  certainly  apparent. 

Consideration  such  as  the  foregoing  will  naturally  cause  practical 
dairymen  to  hesitate  regarding  the  installation  of  milking  machinery 
until  further  careful  experimentation  yields  fuller  information  and 
justifies  more  positive  conclusions. 


32          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIEYING. 

RESULTS    OF    EXPERIENCE    WITH    MILKING    MACHINES    AS 
REPORTED  BY  DAIRYMEN. 

In  order  to  have  an  expression  of  opinion  direct  from  the  dairymen 
regarding  the  use  of  cow  milkers,  a  number  of  questions  were  sent  to  all 
dairymen  who  were  known  to  have  used  machines  for  any  length  of  time. 

All  of  the  1 1  dairymen  who  reported  said  the  effect  of  the  machines 
upon  the  teats  and  udder  of  the  cows  was  favorable;  likewise  the  effect 
upon  hard  milkers,  nervous  cows,  and  kickers. 

Nine  reported  that  heifers  adapted  themselves  readily  to  the 
machines;  1  stated  that  heifers  took  to  them  more  readily  than  old 
cows,  and  1  reported  no  experience.  Of  the  live  instances  where  1 
man  handled  '2  machines,  the  average  number  of  cows  milked  was  23 
and  the  average  time  required  to  milk  them  was  47  minutes,  or  prac- 
tically '2  minutes  per  cow.  In  the  one  instance  where  1  man  han- 
dled 3  machines  he  milked  30  cows  in  *>()  minutes.  In  the  case  where 
'2  men  handled  4  machines  27  cows  were  milked  in  -iO  minutes.  In 
the  two  instances  where  '2  men  handled  5  machines  they  milked  an 
average  of  52£  cows  in  (>8^-  minutes.  Where  '2  men  handled  0  machines 
the  time  required  was  1  minute  per  cow.  Again  where  3  men  and  bo}Ts 
were  just  learning  they  milked  30  cows  in  55  to  75  minutes. 

Some  of  the  advantages  of  the  machines  reported  were  less  help, 
less  time  required,  and  more  and  cleaner  milk.  One  dairyman  reported 
the  cost  to  be  a  disadvantage,  and  another  considered  it  a  disadvantage 
to  run  the  gasoline  engine  in  winter. 

From  1  to  -i  cows  in  the  different  nerds  were  reported  as  refusing  to 
give  their  milk  with  the  machine.  Some  reported  having  this  trouble 
at  first  but  said  that  later  it  disappeared. 

Eight  dairymen  out  of  11  did  not  think  it  necessary  to  strip  the 
cows  after  using  the  machine,  '2  thought  it  advantageous,  and  1  simply 
stated  that  there  was  very  little  milk  left  after  using  the  machines. 

Six  dairymen  stated  that  they  found  little  difference  in  the  amount 
of  milk  produced,  whether  the  cows  were  milked  by  hand  or  machine; 
•i  thought  the  machines  increased  the  How.  and  1  stated  that  the  effect 
of  the  machines  on  production  was  good. 

All  of  the  dairymen  reported  machine  milking  to  be  superior  to  hand 

milking. 

ADDENDUM. 

Since  the  experiments  described  in  this  bulletin  were  conducted 
(August,  1905),  the  condition  of  the  milking-machine  industry  has 
greatly  changed.  Certain  improvements  have  been  made.  For  ex- 
ample, the  milk  ports  thru  the  pulsator  have  been  enlarged;  a  tilter 
between  the  pail  and  the  stanchion  has  been  introduced,  greatly  reduc- 
ing the  number  of  bacteria;  and  the  surging  of  the  milk  in  the  tubes 
has  been  prevented.  The  sanitary  features  have  also  been  improved. 
Over  a  thousand  of  the  machines  arc  now  reported  to  be  in  use. 


II.— BACTERIOLOGICAL  STUDIES  OF  A  MILKING  MACHINE. 

By  W.  A.  STOCKING,  Jr.,  M.  S.  A., 

BacteriologiM,  Storrs  Agricultural  Experiment  Station;  Professor  of  Dairy  Bacteriology, 
Connecticut  Agricultural  College. 


PRODUCTION  OF  SANITARY  MILK. 

At  the  present  time  there  is  a  greater  demand  for  milk  which  has 
been  produced  and  cared  for  under  such  sanitary  conditions  as  to 
insure  its  reaching  the  consumer  in  a  pure,  wholesome  condition  than 
for  any  other  dairy  product.  In  order  to  supply  this  demand  the 
milk  must  reach  the  consumer  in  as  nearly  as  possible  the  condition 
in  which  it  leaves  the  udder  of  the  healthy  cow.  One  of  the  great 
difficulties  in  the  wa}T  of  supplying  consumers  with  such  a  grade  of 
milk  lies  in  the  dirt  and  the  bacterial  contamination  which  it  receives 
before  leaving  the  farm.  As  our  knowledge  of  the  laws  of  sanitation 
and  the  importance  of  pure  foods  becomes  more  widely  disseminated 
among  milk  users  this  demand  for  a  cleaner  and  more  wholesome 
grade  of  milk  will  steadily  increase.  One  of  the  greatest  problems 
for  the  milk  producer  to  solve  is,  therefore,  that  of  producing  such  a 
grade  of  milk.  A  few  dairymen  are  now  producing  a  high  grade  of 
milk  under  such  sanitary  conditions  as  reduce  the  dirt  and  bacterial 
contamination  to  a  minimum.  For  this  purpose  covered  milk  pails 
are  commonly  used,  and  great  care  is  taken  that  the  cows,  the  stables, 
the  utensils,  and  the  milkers  shall  be  kept  as  clean  as  possible.  All 
this  extra  care  and  labor  is  costly,  and  the  milk  thus  produced  demands 
a  price  considerably  above  the  ordinary  market  price.  This  grade  of 
milk  tills  a  limited  demand  for  those  who  can  afford  to  pay  the  con- 
siderably increased  price,  but  the  problem  of  the  milk  supply  for  our 
cities  will  not  be  solved  until  the  general  consumer  can  be  supplied 
with  pure,  clean  milk  at  a  reasonable  price. 

While  the  exercise  of  this  increased  care  and  the  use  of  the  covered 
pail  reduce  the  chance  for  external  contamination  very  materially  and 
greathT  improve  the  quality  of  the  milk,  the  ideal  condition  would  lie 
to  draw  the  milk  directly  from  the  udder  into  a  closed  receptacle  with- 
out any  chance  for  external  contamination.  This  idea  has  stimulated 
in  no  small  degree  the  inventors  of  the  various  styles  of  milking 
machines  which  have  been  developed  during  the  last  few  years. 

33 


84          THE    MILKING    MAOHINP]    Aft    A    FACTOR    IN    DAIRYING. 

While,  it  has  been  possible  with  some  of  these  machines  to  draw  the 
milk  thru  closed  tubes  directly  from  the  udder  into  a  closed  recep- 
tacle, none  of  them  have  thus  far  proved  satisfactory  in  all  respects. 
If  a  machine  could  be  devised  which  would  be  satisfactory  in  its  effect 
upon  the  cow  and  upon  the  yield  of  milk,  arid  which  can  be  cleaned 
with  reasonable  ease  and  at  the  same  time  all  contact  of  the  milk  with 
the  surroundings  could  be  prevented,  it  would  go  far  toward  solving 
the  problem  of  providing  the  public  with  clean,  wholesome  milk. 

EXPERIMENTS  DESIGNED  TO  TEST  THE  SANITARY  CHARACTER 
OF  MACHINE-DRAWN  MILK. 

In  planning  this  experimental  work  the  writer  had  three  main 
objects  in  view:  (1)  To  determine  the  germ  content  of  machine-drawn 
milk  in  comparison  with  that  drawn  by  hand;  ('2)  to  test  the  efficiency 
of  the  machine  in  reducing  the  germ  content  to  the  minimum,  and 
thus  to  determine  its  value  in  the  production  of  "sanitary"  milk;  and 
(3)  to  determine  the  amount  of  care  necessary  to  keep  the  machines  in 
a  sterile  condition. 

Two  farms  were  chosen  for  this  work;  one,  a  dairy  where  the  sani- 
tary conditions  were  about  the  average  existing  in  dairy  barns,  and 
the  other  representing  a  higher  class  of  dairy  barns  in  which  sanitary 
milk  might  be  produced. 

EXPERIMENTS   AT   FARM    XO.   1. 

The  first  barn  selected  for  this  series  of  experiments  is  believed  to 
represent  about  the  average  sanitaiy  conditions  of  dairy  barns  in  the 
principal  dairy  sections  of  the  country.  As  may  be  seen  by  refer- 
ring to  the  illustration  (pi.  4,  tig.  '2),  the  barn  itself  was  in  good  condi- 
tion. The  feeding  alley,  mangers,  and  drop  were  all  of  cement,  while 
the  stable  floor  on  which  the  cows  stood  was  of  plank.  The  stable  had 
been  whitewashed  and  was  fairl^v  clean,  but  no  special  care  was  exer- 
cised each  day  in  cleaning  either  the  stable  or  cows  nor  in  handling 
the  milk. 

METHOD    OF    EXPERIMENT. 

In  order  to  eliminate  the  difference  due  to  the  germ  content  of 
individual  udders  and  give  greater  practical  value  to  the  work,  two 
lots  of  10  cows  each  were  used  in  this  series  of  tests.  One  of  these 
lots  was  milked  by  machine  and  the  other  by  hand.  Samples  from 
the  mixt  milk  of  each  lot  of  10  cows  were  taken  as  soon  as  the  milking 
was  completed  and  were  carried  to  the  laboratory.  Owing  to  circum- 
stances it  was  impossible  to  plate  samples  at  night.  The  evening 
samples  were  therefore  placed  on  ice  until  the  following  morning. 
The  morning  samples  were  also  placed  on  ice  as  soon  as  obtained  and 
plated  after  they  were  thoroly  chilled.  It  is  of  course  possible  that 
there  may  have  been  some  slight  increase  in  numbers  in  the  samples 


BACTERIOLOGICAL    STUDIES. 


35 


of  evening's  milk  before  they  were  plated.  It  is  probable,  however, 
that  there  was  normally  no  appreciable  increase  but  rather  a  decrease 
in  total  numbers,  due  to  the  natural  dropping  out  of  certain  species  in 
accordance  with  the  so-called  "germicidal  property'1  of  milk.  In 
either  case  the  value  of  the  results  is  not  affected,  since  the  hand- 
drawn  and  machine-drawn  samples  were  treated  alike  in  every  case, 
and  it  is  the  comparison  of  these  which  is  of  value.  In  order  to 
determine  the  numbers  of  bacteria  existing  in  the  milk,  plate  cultures 
were  made  in  litmus  sugar  gelatin. 

In  plating  any  sample  of  milk  it  is  of  course  a  problem  to  know  just 
what  dilution  to  use  in  order  to  obtain  the  proper  number  of  colonies 
in  the  culture  plate.  In  order  to  be  sure  of  getting  satisfactory 
results  two  or  three  differ- 
ent dilutions  were  used  in 
plating  the  milk,  duplicate 
plates  being  made  from 
each  dilution.  In  most  ex- 
periments all  the  plates 
developed  with  satisfac- 
tory numbers  and  the  aver- 
age of  all  was  taken  as  rep- 
resenting the  number  of 
bacteria  present  in  the 
milk,  so  that  the  figures 
given  in  this  report  repre- 
sent the  averages  from  the 
four  or  six  plates  made  by 
the  two  or  three  dilutions 
from  the  same  sample  of 
milk.  As  soon  as  the  plate 
cultures  were  made  they 
were  placed  in  an  incubator 

in  which  a  constant  temperature  of  TO    F.  was  maintained, 
cultures  were  allowed  to  develop  for   live  days,  at  the  end 
time  they  were  studied  for  the  following  points: 

1.  The  total  number  of  bacteria. 

'2.  The  number  of  acid-producing  bacteria. 

•'>.  The  number  of  liquefying  or  enzyme-producing  bacteria. 

The  total  number  of  bacteria  indicates  the  amount  of  the  contami- 
nation the  milk  has  received.  The  number  of  acid-producing  organ- 
isms was  determined  separately  from  the  others  because  of  their 
importance  in  connection  with  the  keeping  properties  of  the  milk. 
The  group  of  liquefying  organisms  includes  those  species  which  gain 
access  to  the  milk  thru  tilth  and  tend  to  produce  putrefactive  changes 
in  it.  It  is  this  group  especially  which  it  is  desirable  to  exclude 
from  milk  intended  for  human  consumption,  since  it  is  believed  that 


it  farm    No.    1. 
fur  live 
the  atmosphere 


Here  the 
of  which 


36          THE    MILKING    MACHINE    Aft    A    FACTOR    IN    DAIRYING. 

members  of  this  group  sire  associated  with  certain  digestive  troubles, 
especially  in  children.  It  was  believed  that  si  study  of  this  group 
might  show  interesting  comparisons  between  hand-drawn  and  machine- 
drawn  milk.  The  comparative  data  upon  the  keeping  quality  of  the 
different  samples  of  milk  were  obtained  by  taking  subsamples  as  soon 
as  the  milk  reached  the  laboratory,  one  of  these  subsamples  being 
kept  at  a  constant  temperature  of  70 J  F.  and  the  other  placed  in  an 
ice  chest  where  the  temperature  did  not  vary  greatly  from  50°  F.,  or 
that  which  is  commonly  maintained  in  home  refrigerators. 

FIRST    TREATMENT    OK    THE    MILKING    MACHINES. 

As  previously  stated,  one  of  the  points  which  the  writer  wished  to 
determine  was  the  amount  of  care  necessary  for  the  proper  cleansing 
of  the  machines  after  each  milking.  For  this  purpose  the  treatment 
which  the  machines  received  was  varied  from  time  to  time  during  the 
period  covered  by  the  tests.  The  treatment  which  the  machines 
received  is  used  as  a  basis  for  grouping  and  tabulating  the  results,  and 
the  effect  of  the  various  methods  used  in  washing  the  machines  will  be 
brought  out  in  the  succeeding  tables. 

In  the  iirst  place,  it  was  desired  to  determine  the  efficiency  of  the 
method  already  in  operation  on  the  farm  for  washing  the  machines. 
This  method  was  as  follows:  After  the  morning  milking  the  machines 
were  washt  in  water  to  which  had  been  added  some  sal  soda  or  other 
washing  powder.  They  were  then  rinsed  by  pumping  hot  water  thru 
them.  After  the  night  milking  they  were  simply  rinsed  with  cold 
water.  The  machines  were  not  taken  apart.  The  germ  content  of 
the  milk  drawn  with  the  machines  treated  in  this  way,  in  comparison 
with  milk  drawn  by  hand,  is  shown  in  Table  -i. 

TABLE  4. — Comparison  of  results  of  h<nt(l  and  machine  milkiruj — machines  vault t  after 
worning  milking  u'ithwater  and  sal  soda,  tl/en  riiwd  irlth  u-ann  water;  after  night  milk- 
ing, simply  rinsed  with  cold  tenter — machines  not  taken  apart . 


Date. 


Number  <>i  bacteria   ]>er  culm 


E>  Too  numerous  to  count  with  the  dilution  used. 


EXPERIMENTS    AT    FARM    NO.   1.  37 

It  will  be  noticed,  in  the  column  marked  "Total  bacteria,"  that  the 
machine-drawn  milk  contained  in  every  case  decidedly  larger  numbers 
of  bacteria  than  did  the  milk  drawn  by  hand  at  the  .same  milking. 
The  numbers  obtained  in  the  hand-drawn  milk  are  about  what  might 
be  expected  from  the  ordinary  method  of  hand  milking  in  a  barn  of 
this  o-rade,  but  the  numbers  in  the  machine-drawn  milk  are  very  much 

<?5  •/ 

higher  than  they  should  be  in  fresh  milk.  It  will  be  noticed  also,  by 
the  stud}-  of  the  column  marked  "Acid  bacteria,"'  that  the  bacteria  in 
the  machine-drawn  milk  were  chiefly  acid-producing  organisms,  in 
many  cases  as  high  as  99  per  cent  being  such.  This  proportion  of 
acid  bacteria  is  much  larger  than  would  result  from  ordinary  stable 
contamination,  and  indicates  that  the  machines  were  not  being  prop- 
erly cleaned  and  that  they  furnished  a  breeding  place  for  the  acid- 
producing  species.  This  would  result  in  the  milk  that  was  drawn 
thru  these  machines  becoming  heavil}T  inoculated  with  acid  organisms. 
It  is  most  significant  to  note  that  in  spite  of  the  extremel}r  high  total 
number  of  bacteria  in  the  machine-drawn  milk  the  number  of  lique- 
fying organisms  is  in  nearly  every  case  very  much  smaller  than  in 
the  corresponding  hand-drawn  milk.  When  we  remember  that  it  is 
this  group  which  contains  putrefactive  organisms  which  get  into  milk 
principally  from  stable  tilth,  and  that  these  organisms  producing  putre- 
factive fermentations  in  the  milk  are  believed  to  cause  serious  digest- 
ive troubles  with  children,  the  significance  of  these  figures  is  at  once 
apparent.  xVs  a  result  of  the  machine-drawn  milk  being  protected 
from  external  contamination  the  number  of  organisms  of  this  group 
which  gained  access  to  the  milk  was  very  materially  reduced.  At  the 
close  of  this  period,  after  it  was  thoroly  demonstrated  that  the  care 
which  the  machines  were  receiving  was  not  sufficient  to  keep  them  in 
a  sterile  condition  and  that  they  served  as  breeding  places  for  bacteria, 
a  different  method  of  cleansing'  was  adopted. 


SECOND    TREATMENT    OF    THE    MACHINES. 


All  the  rubber  tubes  and  teat  cups  were  taken  apart.  It  was  found 
that  the  long  tubes  contained  considerable  quantities  of  decaying 
milk,  thus  making  them  decidedly  insanitary.  In  order  to  cleanse 
these  they  were  run  thru  a  clothes  wringer  twice  in  order  to  loosen 
and  squeeze  out  any  dirt  that  might  be  in  them.  All  parts  of  the 
machine  were  then  placed  in  a  boiler  arid  thoroly  boiled.  After  the 
boiling  the  parts  were  placed  in  a  weak  brine  solution,  where  they 
remained  until  milking  time.  Another  series  of  tests  was  then  made, 
during  which  time  the  machines  received  the  following  treatment: 
After  each  milking  the  machines  had  cold  water  pumped  thru  them 
immediately.  They  were  then  washed  with  hot  water  containing 
washing  powder,  rinsed  in  boiling  water,  and  placed  in  brine  until 
needed  for  the  next  milking'.  The  results  obtained  from  the  tests 


38 


THE    MILKING    MACHINE    AS    A    ITACTOR    IN    DAIRYING. 


made  while  the  machines  received  this  treatment  are  given  in  Table 
5,  the  first  part  showing1  the  results  from  the  morning  milkings  and 
the  second  part  the  results  from  the  night  milkings. 

TABLE  5. — Comparison  of  results  of  hand  and  machine  milking — machines  taken  apart 
mid  cleaned;  rinsed,  in  cold  water,  then  hot  sal  soda  water,  then  in  boiling  water,  and 
placed  in  brine  till  used;  rinsed  just  before  use. 

NIGHT  MILKING. 


Date. 

Xo-  t)f        Method  of 

uS.      milkin*- 

Number  of  bacteria  per  cubic 
centimeter  of  milk. 

Hours  to  curd- 
ling at— 

Total  bac- 
teria. 

Acid  bac- 
teria. 

324,050 
382,  250 
10,  000 

teria. 

70°  F.     50°  F. 

Julv  28  

|        33 

Machine  

347,800 

420,  750 
39,  500 

13,300 
31,500 
9,000 

43 
32 
«30 
"30 
36 
36 
42 
"30 
«30  j 
"30 
"30 
28 
a  30 

41 

ii  30 

35 
31 

50 
39 
"30 
49 
63 
a  54 
102 
88 

93 
76 
65 
69 
68 
91 
67 

65 

Julv  29  

1        41     Machine  

Julv  30  

\       45     Machine  

622,  000 
1,036,000 
30,  500 
681,500 
332,  000 
633.  500 
223,  7.50 
1,302,666 
242,  250 
582,  500 
781,500 
197,500 

i  an,  ooo 

12*.  000 
18,333 
127,  000 
69,  000 
500,  500 
135,7.50 
964,  500 
97,000 
355,  500 
160,  750 
51,000 

10,500 
16,500 
1,041 
82,  750 
57,  332 
31.375 
10,  625 
279,000 
52,  625 
99,500 
74,  125 
13,  375 

August  2  

1        46 
|        65 

Machine  

August  3.  

1        71 

Machine  

August  4  

"]         72 

I        77 

Hand  
Machine  

August  5  

1        78 
(        83 

Machine  

)'       89  '  Machine  

Average  

",t        90 

Hand  
fMachine  

327,412 
693,  488 

119,110 
372,  687 
36.4 
53.7 

27,818 
79,  143 
8.5 

Percentage  

(Machine  

i 

t  liana  

11.4 

MORNING  MILKING. 


A  comparison  of  the  column  marked  "Total  bacteria"  in  the  above 
table  with  the  corresponding  column  in  Table  -i  shows  a  very  marked 
diminution  in  the  bacteria  found  in  the  machine-drawn  milk.  While 
the  average  for  the  machine-drawn  milk  in  Table  -i  was  in  round  num- 
bers 2,790,0<>0,  the  average  in  Table  5  was  327, -100  for  the  night  milk- 
ing and  153,6<>0  for  the  morning  milking.  At  the  same  time  that  this 
decided  falling  off  in  the  numbers  of  bacteria  in  the  machine-drawn 
milk  occurred,  the  bacteria  in  the  hand-drawn  milk  in  the  nisrht 


EXPERIMENTS    AT    FARM    NO.    1. 


39 


samples,  as  shown  in  Table  5,  was  not  materially  smaller  than  in  Table 
•i,  while  in  the  morning  milk  the  numbers  were  decidedly  smaller. 
These  differences  are  no  greater  than  would  be  expected  in  any  series 
of  bacterial  tests  taken  under  similar  circumstances.  In  the  morning's 
milk,  as  shown  in  Table  5,  the  numbers  of  bacteria  were  also  decidedly 
smaller  in  the  machine-drawn  milk.  The  most  important  fact  to  be 
noted  here  is  the  changed  relation  existing  between  the  bacteria  in  the 
machine-drawn  and  hand-drawn  milk.  As  shown  in  Table  -i,  before 
the  machines  were  cleaned  the  milk  drawn  thru  them  contained  many 
times  more  bacteria  than  did  the  hand-drawn  milk,  while  after  the 
cleaning,  and  with  the  brine  treatment,  the  machine-drawn  milk  con- 
tained approximately  only  one-half  as  many  bacteria  as  were  contained 
in  the  milk  drawn  by  hand. 
A  study  of  the  acid-form- 
ing organisms  reveals  the 
fact  that  it  was  in  this 
group  that  the  decrease 
in  numbers  took  place. 
While  in  the  machine- 
drawn  milk,  in  Table  4, 
there  was  an  average  of 
over  90  per  cent  of  acid- 
producing  organisms,  in 
Table  5  the  percentage  of 
these  bacteria  was  36.4 
(night)  and  52. 8  (morning). 
This  decrease  in  the  acid- 
forming  bacteria  in  the  ma- 
chine-drawn milk  in  this 
series  of  tests  completely 
reversed  the  relation  exist- 
ing between  the  bacteria  found  in  the  machine-drawn  and  hand-drawn 
milk,  as  shown  in  Table  4.  In  this  series  of  tests  it  will  be  noticed 
that  in  almost  every  case  the  machine-drawn  milk  contained  decidedly 
smaller  total  numbers  of  bacteria  than  did  the  corresponding  hand- 
drawn  milk.  The  same  relation  exists  in  the  acid  organisms,  the 
machine-drawn  milk  containing  both  a  "lower  total  number  and  a  lower 
percentage  of  acid  organisms  than  did  the  corresponding  hand-drawn 
milk.  The  night's  milk  as  shown  in  Table  5  contained  an  average  of 
36. -4  per  cent  of  acid  organisms  for  the  machine-drawn  milk  as  against 
53.7  per  cent  for  the  hand-drawn  milk,  and  in  the  morning's  milk 
these  percentages  were  52.8  for  the  machine-drawn  and  64.8  for  the 
hand-drawn  milk.  .Essentially  the  same  relation  in  regard  to  the 
liquefying  organisms  in  the  machine-drawn  and  hand-drawn  milk  is 
shown  in  Table  5  as  was  shown  in  Table  4.  The  average  percentage 


40 


THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 


of  liquefiers  in  the  machine-drawn  milk  of  the  night  samples  was  8.5, 
while  it  was  11.4  in  the  hand-drawn  milk.  In  the  morning's  milk,  that 
drawn  by  machine  contained  an  average  percentage  of  9.9  and  the 
hand-drawn  12.fi  of  liquefiers.  The  principal  value  of  these  two  tables 
lies  in  the  fact  that  they  show  such  a  marked  decrease  in  the  bacteria 
found  in  the  machine-drawn  milk,  this  decrease  being  the  result  of  the 
greater  care  used  in  the  washing  of  the  machine. 


THIRD    TREATMENT    OF    THE    MACHINES. 


In  spite  of  the  greatly  reduced  number  of  bacteria  obtained  in  the 
machine-drawn  milk,  the  writer  believed  that  the  machines  were  not 
being  properly  sterilized.  To  test  this,  cultures  were  made  by  shaking- 
sterile  water  in  the  rubber 
tubes  after  they  had  been 
washed  as  usual.  The  plate 
cultures  made  in  this  way 
showc  d  that  the  short  tubes 
and  the  ends  of  the  long 
ones  contained  only  small 
numbers  of  bacteria,  but 
that  the  central  part  of  the 
three  long  rubber  tubes 
was  still  filled  with  bacte- 
ria, which  were  not  being 
killed  or  removed  by  the 
method  used  for  cleaning 
the  machines. 

A  further  test  of  this 
point  was  made  in  connec- 
tion with  experiments  77 
and  78  by  milking  two  cows 
with  an  entirely  new  machine.  The  milk  thus  obtained  showed  a  germ 
content  of  17,<>12  bacteria  per  cubic  centimeter.  At  the  same  time  the 
milk  drawn  into  the  machine  which  was  in  regular  use  contained  223,750 
bacteria.  This  great  difference  in  numbers  of  bacteria  found  in  the 
milk  drawn  into  the  old  and  the  new  machines,  together  with  the  fact 
that  such  large  numbers  were-  found  in  the  tubes  used  on  the  old 
machine,  was  considered  definite  proof  that  the  daily  care  used  in  clean- 
ing the  machines  was  not  sufficient  to  prevent  their  becoming  breeding 
places  for  bacteria.  Another  change  was  therefore  made  in  the  treat- 
ment of  the  machines,  and  the  results  obtained  are  given  in  Table  (>. 

On  these  days  the  machines  were  rinsed  with  cold  water  as  usual. 
They  were  then  placed  in  water  containing  a  small  amount  of  pow- 
dered borax  and  boiled  for  at  least  one-half  hour.  The  machines  were 
then  taken  out  and  hung  up  in  the  open  air  until  needed  for  use. 


EXPERIMENTS    AT    FARM    NO.    1. 


41 


This  treatment  was  given  the  machines  on  but  two  days.  As  shown 
in  the  table,  the  average  for  the  machine-drawn  milk  was  28,562  and 
for  the  hand-drawn  48,125  bacteria  per  cubic  centimeter.  This  is  a 
much  smaller  number  than  had  been  previously  obtained  by  either  the 
machine  or  hand  method,  but  the  relative  numbers  are  not  materially 
different  from  those  found  in  the  previous  series  of  experiments  where 
the  machines  were  soaked  in  brine.  These  results  seem  to  indicate 
that  the  boiling  in  a  weak  borax  solution  and  the  soaking  in  the  brine 
were  about  equally  effective  in  freeing  the  machines  of  bacteria. 

TABLE  6. — Comparison  of  results  of  hand  and  machine  milking — machines  rinsed  with  cold 
water,  boiled  m  water  containing  borax,  then  hung  up  'in  open  air  till  used. 


Aug"st 


Date. 

No.  of 
experi- 
ment. 

f     95 
I     9(5 
(    101 
I    101  A 

Time  of 
milking. 

Night... 

Method  of 
milking. 

Number  of  bacteria  per  cubic 
centimeter  of  milk. 

Hours  to  c 
dling  at— 

ir- 

Total 
bacteria. 

Acid 
bacteria. 

Liquefy- 
ing 
bacteria. 

70°  F.      50° 

«30  ! 
41  ! 
»54 

F. 

Machine  

.       35,125 

4,625 
9,  125 
3,000 

o 

13,  500 

11,125 
16,625 
4,500 
0 
17,000 

86 
96 
111 

.   ...do 

Hand 

45  000 

do  .  . 

Machine 

22,  000 

7  .S75 

do 

do 

Averages  

102 

do 

Hand 

51,250 

43 

75 

(Machine  

28,  562 
48,  1-25 

3,  812 
11,312 

7,812 
16,812 

42 

42 

99 

86 

Percentages. 

(Machine  

13.4 
23.5 

27  4 
35.0 

(Hand  

[ 

1 

a  Curdled  at  night — exact  time  not  determined. 

ForHTII    TREATMENT    OF    THE    MACHINES. 

On  the  night  when  samples  101  and  102  were  taken,  a  third  sample — 
marked  in  the  table  "101A" — was  obtained  b\-  milking  two  cows  into 
a  machine,  all  parts  of  which  had  been  placed  in  a  box  and  subjected 
to  live  steam  for  20  minutes.  The  results  obtained  in  this  way  are 
very  striking.  The  number  of  bacteria  contained  in  the  milk  thus 
taken  was  7.875,  while  the  number  from  the  other  machines  was  22,000 
and  in  the  milk  drawn  bv  hand  51.250. 


FIFTH    TREATMENT    OF    THE    MACHINES. 

At  this  point  another  change  in  the  treatment  of  the  machines  was 
made.  After  being  used  at  night  they  were  rinsed  with  cold  water, 
then  washed  with  hot  water,  without  the  addition  of  any  borax.  The 
results  obtained  when  the  machines  were  thus  treated  are'sdven  in 

m 

Table  7.  After  the  morning  milking  the  machines  were  rinsed  with 
cold  water  as  usual.  They  were  then  washt  in  hot  water  contain- 
ing borax,  after  which  all  the  rubber  parts  were  placed  in  brine 
until  needed  for  the  evening  milking.  The  results  obtained  from  this 
treatment  are  shown  in  Table  (S. 


42 


THE    MILKING    MACHINE    AS    A    FACTOK    IN    DAIRYING. 


TABLE  7. — Comparison  of  results  of  hand  and  machine  milking — machines  washt  in  cold 
water  and  then  in  hot  sal  soda  water,  no  borax  being  used. 


Date. 

No.  of 
experi- 
ment. 

Time  of 
milking. 

Morning 
do 

Method  of 
milking. 

Number  of  bacteria  per  cubic     Hours  to  cur- 
centimeter  of  milk.                dling  at— 

Total 
bacteria. 

Acid 
bacteria. 

Lique- 
fying 
bacteria. 

70°  F. 

50°  F. 

August 
August 
August 
August 
August 
August 
August 

A 

P( 

8  

9  

1       97 
\        9* 
(      103 
'1       104 
j      109 
I       110 
1       115 
'1       116 
(       121 

.    Machine  
Hand 

.      268,  666 
296  250 

49,  666 
122,  000 
500 
28,000 
2,000 
5,875 
5,  125 
15,  750 
7,125 
326,  000 
4,000 
4,625 
1,  625 
2,  375 

77,999 
103,  375 
625 
32,  250 
4,125 
19,  375 
6,  625 
9,  625 
9,250 
92,000 
6,  375 
1,525 
3,000 
250 

37 

28 
38 
32 
35 
30 
37 
37 
a  41 
26 
35 
35 
a  41 
35 

83 
63 
96 
63 

58 
«41 
"65 
a  65 
(») 
a  41 
(") 
(&l 
(6) 
'< 

do.. 

.    Machine  

5,  875 

10  

do., 
do 

.    Machine  
Hand 

.:      14,000 
102  950 

do.. 

.    Machine  

72^  375 
'      54  625 

12 

do 

Hand 

do.. 

.    Machine  

.!      64,125 

13  

1         122 
f       127 
)       128 
f      133 
1      134 

do  .. 
do.. 

.]  Hand  
.    Machine  

944,  000 
84,  375 

do.. 

.    Machine  

76,  750 

do 

Hand 

42,  625 

/Machine  

S3,  738 

10,006         15,42*             38 
78,089         3.5,914             32 

70 
58 

>rcentage. 

'  \Hand  
(Machine  

12.0             18.2 
32.  •_>             16.  5 

"Curdled  at  night— exact  time  not  determined. 
'>Xot  curdled  by  August  19. 

In  four  of  the  experiments  shown  in  this  table  the  machine-drawn 
milk  contained  a  much  smaller  number  of  bacteria  than  did  the  corre- 
sponding- hand-drawn  milk. 
In  some  of  these  cases  the 
difference  is  very  great,  es- 
pecially in  experiments  103 
and  It)!,  and  1<>1>  and  110, 
where  the  numbers  in  the 
machine-drawn  milk  were 
small.  In  the  other  three 
experiments,  however,  the 
machine-drawn  milk  con- 
tained larger  numbers  of 
bacteria  than  did  that 
drawn  by  hand.  Still,  the 
averages  are  decidedly  in 
favor  of  the  machine- 
drawn  milk. 

The      results      obtained 
from      the     night's     milk 
where   the   machines  were 
washt  in  borax  water  and  soaked  in  brine  will  be  found  in  Table  S. 


EXPERIMENTS    AT    FARM    NO.   1. 


43 


TABLE  8. — Comparison  of  results  of  hand  and  machine  milking — machines  wasld  in  cold 
water,  then  in  borax  water,  <uid  all  rubber  parts  placed  in  brine  till  used. 


Date. 

No.  of 
experi- 
ment. 

Time  of 
milking. 

Night  
do  

Method  of 
milking. 

Number  of  bacteria  per  cubic 
centimeter  of  milk. 

Hours  to  cur- 
dling at— 

Total 
bacteria. 

Acid 
bacteria. 

Liquefy- 
ing 

bacteria. 

70°  F.     50°  F. 

\ugust  9 

f  107  • 
{   107A 

Machine... 
do  

15,  750 
2,  375 
115,500 
31,  750 
8,  750 
56,  625 
^,625 
T9,  250 
115,250 
17,  750 
13,  500 
9,  125 
1,213.000 
49,  875 
27,625 
21,000 
4,625 

2,250 
1,250 
40,  500 
13,000 
750 
7,  125 
6,500 
3,  625 
42,  250 
1,625 
500 
2,  250 
12,250 
7,000 
1  ,  875 
250 
625 

3,500 
1,250 
34,625 
7,  375 
1,375 
22,  250 
15,  875 
1,  750 
25,  375 
2,  2,50 
2,666 
625 
11,875 
0 
1,000 
1,625 
0 

43              87 
68          (6) 
38              71 
50              101 
a  78         ('-) 
38               73 
"30               76 

a  54 

45         C<) 
45         ('•) 
49         ('') 
89        ('>) 

50        CM 

I   108 
I    113 
113A 
114 
119 
ll't  \ 

do 

Hand  .     . 

do 

Machine  

do 

do 

\ugust  1  1 

do 

Hand  

do 

Machine 

d  ) 

do 

120 
125 

V>5  \ 

d  > 

Hand  

d  >.... 

Machine  

d  > 

do 

1   126 
|   131 
\  132 
1   137 
<    137A 
1    138 

d  > 

Hand  

d  ..... 

Machine  

August  14 

do 

Hand 

do 

Machine   

do 

do 

Average. 

do 

Hand 

(Machine 

225,917           6,250 
12,975          1,275 
58,500  ,      16,625 

8,125             42               w 
1,733            61        <t>> 
13,812  j           41               66 

{Machine  A  . 

(Hand  

9  '.' 

:>  (i 

{Machine  -V 

13  4 

[Hand 

28.  4             23.  6 

"Curdled  in  night — exact  time  not  determined. 


,  curdled  by  August  19. 


In  a  part  of  those  experiments  the  results  are  very  much  in  favor  of 
the  machines,  while  in  the  last  three  tests  the  comparison  is  in  favor 
of  the  hand-drawn  milk. 
This  seems  to  be  due  to  an 
unusually  small  number  of 
bacteria  in  the  hand-drawn 
milk  rather  than  to  any 
marked  increase  in  the 
number  in  the  machine- 
drawn  milk,  with  the  one 
exception  of  experiment 
181.  In  this  case1  it  is  evi- 
dent that  something  decid- 
edly wrong  must  have  oc- 
curred to  give  the  milk  such 
an  abnormally  high  germ 
content.  If  we  leave  this 
one  experiment  out  of  the 
averages  we  have  for  the 
machine-drawn  milk  an  av- 
erage of  28.500,  instead  of 

225.900,    and  for    the    hand-drawn    mi!k   00.225.    instead   of 
This  would  o-ive  a  showing  greatlv  in  favor  of  the  machines. 

&  CJ     <^  * 

case  in  the  preceding  tables. 


per 


58.500. 
is  is  the 


44          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 


TREATMENT  OK  THE  MACHINES. 


In  connection  with  the  experiments  shown  in  the  preceding  table, 
'2  cows  were  milked  each  night  with  a  machine  which  had  been  sub- 
jected to  live  steam  for  '20  to  80  minutes.  The  results  of  the  milk 
thus  obtained  are  seen  in  the  experiments  marked  "A"  in  the  table. 
It  will  be  seen  that  the  numbers  of  bacteria  in  this  milk  are  very  much 
smaller  than  those  obtained  by  the  other  machines,  running  as  low  as 
2,875  bacteria  per  cubic  centimeter  in  experiment  107A.  These  results 
seem  to  indicate  that,  even  with  the  care  that  the  regular  machines 
were  receiving,  they  still  harbffred  relatively  large  numbers  of  bacteria 
which  contaminated  the  milk  drawn  thru  them.  It  will  also  be  noticed 
that,  even  with  the  machine  receiving  the  steam  treatment,  the  germ 
content  of  the  milk  increased  quite  rapidly  from  day  to  day  until  it 
was  about,  the  same  as  in  the  regular  machine-drawn  milk.  This  is 
regarded  as  an  indication  that  the  steam  treatment  given  was  not  suf- 
ficient to  completely  sterilize  this  machine,  so  that  the  bacteria  gradu- 
ally accumulated  in  the  tubes.  It  was  not  possible  to  get  any  pressure 
in  the  box  used  for  steaming  this  machine,  and  it  is  very  probable  that 
the  temperature  of  the  inside  of  the  long  rubber  tubes  did  not  reach 
that  of  the  steam,  and  hence  did  not  become  sufficiently  heated  to  kill 
the  bacteria  in  them. 

KEEPING    QUALITIES    OF    THE    MILK. 

As  stated  at  the  beginning  of  this  discussion,  an  attempt  was  made 
to  determine  the  keeping  qualities  of  the  milk  by  taking  two  subsam- 
ples  as  soon  as  the  milk  reached  the  laboratory  and  keeping  one  of 
these  at  a  constant  temperature  of  70°  F.  and  the  other  at  50°  F. 
During  the  day  these  samples  were  watched  and  the  time  at  which 
they  curdled  was  recorded.  It  was,  of  coursc.*impossible  to  watch 
the  samples  during  the  night,  so  that  in  the  case  of  many  of  them  the 
exact  time  of  curdling  could  not  be  determined.  Where  the  samples 
curdled  during  the  night  the  time  of  curdling  was  arbitrarily  given 
as  midnight,  and  all  such  results  are  indicated  in  the  table. 

The  temperature  of  70°  F.  was  taken  as  representing  fairly  well  the 
ordinary  room  temperature  during  the  warm  season,  and  that  of  50° 
F.  as  representing  the  normal  temperature  of  the  refrigerator  in  the 
household. 

The  records  of  the  time  of  curdling  for  the  different  samples  are 
given  in  the  various  tables.  It  is  not  always  easy  to  determine  why  a 
certain  sample  of  milk  should  curdle  when  it  does.  In  general,  nor- 
mal milk  becomes  sour  and  curdles  in  proportion  to  the  number  of 
bacteria  contained,  but  this  relation  is  true  only  between  wide  limits. 
Not  infrequently  one  sample  containing  twice  the  number  of 
bacteria  contained  bv  another  will  remain  uncurdled  the  longer 


SUMMARY  OF  EXPERIMENTS  AT  FARM  NO.  1. 


45 


time.  There  are,  therefore,  marked  irregularities  when  we  attempt 
to  harmonize  the  keeping  quality  with  the  germ  content.  However, 
taking  a  series  of  samples  containing  a  high  germ  content  and  compar- 
ing with  another  series  with  a  comparatively  low  germ  content,  it  will 
lie  found  that  there  is  an  inverse  relation  existing  between  the  germ 
content  and  the  keeping  quality.  Frequently  the  species  of  organisms 
which  the  milk  contains  has  more  to  do  with  determining  its  keeping 
quality  than  does  the  actual  number  of  bacteria  which  may  be  in  the 
milk.  This  fact  accounts  for  man}"  of  the  apparent  discrepancies 
between  the  germ  content  and  the  keeping  quality.  While  the  results 
given  in  the  preceding  tables  show  many  irregularities,  yet  they  are 
of  considerable  interest,  and  in  the  long  run  are  of  value  as  an  indica- 
tion of  the  keeping  quality  of  the  different  samples  of  milk. 

Sl'MMARY    OF    EXPERIMENTS    AT    FARM    NO.    1. 

In  Table  1)  arc  given  the  averages  for  the  germ  content  and  keeping- 
quality  from  the  six  preceding  tables.  While  these  averages  are  not 
of  as  much  value  as  the  results  of  the  individual  experiments,  they 
give  in  a  general  way  the  relation  existing  between  the  machine-drawn 
and  hand-drawn  milk. 

It  will  be  noticed  in  this  table  that  there  is  a  difference  in  favor  of 
the  keeping  quality  of  the  machine-drawn  milk,  both  in  the  samples 
kept  at  70-  F.  and  in  those  kept  at  50  F.,  the  greater  difference  in 
favor  of  the  machine  milk  being  shown  in  the  samples  which  were 
kept  at  5o  F.  One  important  fact  which  is  shown  in  this  table  is  the 
greatly  increased  keeping  quality  of  the  milk  which  was  drawn  into  the 
steam-sterilized  machine  marked  "A"  in  the  table.  These  samples 
held  at  70-  F.  kept  on  the  average  one-third  longer  than  the  average 
of  the  ordinary  machine-drawn  or  hand-drawn  milk,  while  those  held 
at  50-  F.  had  not  curdled  by  August  11)  when  the  test  ended.  This 
emphasizes  the  importance  and  indicates  the  possibilities  of  greatly 
increasing  the  keeping  quality  by  thoroly  sterilizing  the  machine. 


46 


THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 


EXPERIMENTS    AT    FARM    NO.   2. 

The  conditions  of  cleanliness  existing  in  this  stable  are  considerably 
above  the  average  (fig.  (>.)  From  a  sanitary  standpoint  this  stable 
was  not  as  well  constructed  as  was  the  one  at  farm  No.  1.  The  stable 
is  entirely  below  ground  on  the  west  and  north  sides,  but  receives  a 
good  supply  of  light  from  the  south  and  east.  The  feeding  alley  and 
mangers  are  made  of  cement,  but  the  stable  floor,  the  drop,  and  the 

main  floor  behind  the  cows 
are  made  of  plank.  While 
the  construction  of  the  sta- 
ble itself  is  not  especially 
suited  to  the  production  of 
clean  milk,  considerable 
care  was  taken  to  keep  the 
stable  and  the  cows  as  clean 
as  possible.  Considerably 
more  than  average  care  was 
exercised  in  the  milking 
and  the  subsequent  han- 
dling of  the  milk,  so  that 
this  stable  may  properly 
represent  a  fairly  sanitary 
dairy.  It  is  not  to  be  ex 
pected  that  the  germ  con- 

FIG.   6.—  Bacteria  in  atmosphere  of  barn  at  farm    No.   2.  .  . 

Drawing  from  photograph  of  gelatin  plate  exposed  for     tent    OI      milk    produced    111 

^iif-h   «i   sflble  Could'  be  l~er)t 

as  low  as  m  a  stable  con- 

structed on  more  approved  sanitary  plans,  but  the  number  of  bacteria 
found  in  the  hand-drawn  milk,  as  given  in  the  following  tables,  shows, 
however,  that  the  sanitary  conditions  of  the  stable  at  milking  time 
were  excellent.  The  stable  floor  was  always  swept  twenty  minutes  to. 
one-half  hour  before  milking  was  commenced,  and  just  before  milking, 
the  udders  were  wiped  with  a  damp  cloth. 

METHOD    OF    EXPERIMENT. 

In  beginning  the  experiments  in  this  dairy  it  was  desirable,  first,  to 
ascertain  the  relative  germ  content  existing  in  the  machine-drawn  and 
hand-drawn  milk.  For  this  purpose  the  herd  was  divided  into  two 
lots  of  4  cows  each.  One  of  these  groups  was  milked  by  the  machine 
and  the  other  by  hand  into  an  open  pail  in  the  ordinary  way.  As 
soon  as  the  mi  Iking  was  completed,  samples  were  taken  from  the 
mixt  milk  of  each  group  of  cows  and  these  were  carried  to  the  labor- 
atory for  testing.  The  details  of  these  experiments  are  the  same  as 
those  a  1  read}*  outlined  in  connection  with  the  experiments  at  farm 


twenty  seconds  in  stable  at  milking  time,  showing  the  low 
germ  content  of  the  atmosphere,  34  colonies  per  plate. 


EXPERIMENTS    AT    FARM    NO.    2. 


47 


No.  1.  In  this  series  of  tests  samples  were  taken  at  the  night  milk- 
ing only  and  were  placed  on  ice  until  the  next  morning,  when  the  plate 
cultures  were  made.  It  is  probable  that  the  tigures  given  in  the  tables 
are  slightly  lower  than  would  have  been  obtained  had  the  samples 
been  plated  immediately,  since  there  is  usualhr  a  dropping  out  of  cer- 
tain species  during  the  first  few  hours  after  drawing  the  milk.  In  a 
few  cases  where  the  samples  were  plated  at  night  and  again  the  next 
morning  this  was  shown  to  be  true. 


FIRST   TREATMENT   OF   THE    MACHINES. 


At  the  outset  it  was  desired  to  ascertain  the  efficiency  of  the  milking 
machine  with  the  treatment  it  was  regularly  receiving  on  the  farm. 
Three  days'  tests  were  made  without  altering  the  treatment  which  the 
machines  received  and  the  results  were  compared  with  those  obtained 
from  the  corresponding  samples  drawn  by  hand.  The  results  of  these 
tests  are  given  in  Table  10. 

TABLE  10. — -Comparison  of  results  of  hand  and  machine  milking — machines  rinsed  with 
cold  water,  v;asht  with  warm  water  containing  sal  soda,  then  rinsed,  with  hut  tauter. 


Date. 


Num- 
ber of      Method  of 
experi-       milking, 
ments. 


Bacteria  per  cubic  centimeter  of  milk. 


Hours  to  cur- 
dling at — 


During  this  period  the  machines  were  treated  as  follows:  After 
milking  they  were  rinsed  by  pumping  cold  water  thru  them.  This  was 
followed  \)\  warm  water  containing  some  washing  powder,  com- 
monly sal  soda.  Thov  were  then  rinsed  with  clean  hot  water  and  huno- 

«-  «>  O 

up  in  the  air  until  needed  for  use  at  the  next  milking.     A  o-lance  at 

L  ™  ~ 

the  *' Total  bacteria"  column  in  the  table  shows  the  same  relation  exist- 
ing between  the  bacteria  found  in  the  hand-drawn  and  machine-drawn 
milk  as  was  found  in  the  experiments  at  farm  Xo.  1.  The  number  of 
bacteria  in  the  machine-drawn  milk  was  decidedly  higher  than  in  the 
corresponding  hand-drawn  milk  in  each  experiment,  the  average  for 
the  three  samples  of  machine-drawn  milk  being  172,!).")S  bacteria  per 
cubic  centimeter,  while  the  average  for  the  hand-drawn  milk  is  9, -tod. 
It  will  also  be  seen  that  the  organisms  in  the  machine-drawn  milk  wore 
largely  acid-producing  species.  This  also  corresponds  to  the  conditions 


48          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

found  at  farm  No.  1.  It  is  evident  that  the  milk  became  contaminated 
with  large  numbers  of  acid-producing-  organisms  while  passing  thru 
the  machines.  These  results  seem  to  prove  beyond  question  that  the 
care  which  the  machines  were  regularly  receiving  was  not  sufficient  to 
keep  the  tubes  in  a  sterile  condition  and  they  had  therefore  become 
breeding  places  for  bacteria,  which  were  washt  into  the  milk  when 
the  machines  were  used. 

SECOND    TREATMENT    OK   THE    MACHINES. 

At  this  point  a  slight  change  was  made  in  the  method  of  treating 
the  machines,  and  the  figures  given  in  Table  11  show  the  results  of  two 
days'  tests  with  the  machines  thus  treated. 

TAHLE  11. — Comparison  of  results  of  hand  and  machine  milking — treatment  of  machine  the 
.mmeas  indicated  for  Table  10,  except  that  it  fas  scalded  just  before  use  hi/  pumping 
boiling  ivater  thru  it. 


Date! 

No.  of 
experi- 
ment. 

Bacteria  per  t 

Tl 

ubic  centimeter  of  milk. 

ours  to  cur- 
dling at— 

Method  of 
milking. 

Total 
bacteria. 

Ac  id  bac- 
teria. 

Per  cent 
of  acid 
bacteria. 

Liquefy- 
ing bac- 
teria. 

Per  cent 
of  lique-    7Q 
lying 
bacteria. 

D  F.     50°  F. 

J  ill  v  2-1  

f     «  13 

Machine... 
Hand  
Machine..  . 
Hand 

22ti,  700 
11,850 
12.1100 
1,100 

8,883 
2,  GOO 
4,98S 
175 

3 
22 

42 
43 

2.  287 
250 
487 
112 

1 

4 
10 

70            130 
b  54          b  102 
97             171 
64             171 

July  2ti  
Average  . 

1        21 

-  \       22 

(Machine..  . 

119,350 

ti,  935 

1,387 

87              151 
59  !           137 

a  Udders  not  washt.  ''Curdled  at  night — exact  time  not  determined. 

The  machines  were  washt  as  previously  described,  but  they  were 
given  an  additional  scalding  just  before  being  used  by  pumping  boil- 
ing water  thru  them.  It  was  hoped  that  this  might  dislodge  and  wash 
out  any  bacteria  which  might  have  accumulated  in  the  tubes  during 
the  day,  thus  reducing  the  germ  content  of  the  milk.  This  additional 
scalding,  however,  apparently  had  little  effect  upon  the  condition  of 
the  tubes,  since  the  numbers  of  bacteria  were  not  materially  decreased, 
as  will  be  seen  by  a  study  of  Table  11.  Both  the  total  number  and 
the  number  of  acid-producing  organisms  and  also  the  liquefying  bac- 
teria continued  to  be  much  more  numerous  in  the  machine-drawn 
milk  than  in  that  drawn  by  hand. 

It  will  be  noted  that  in  experiment  13  the  udders  were  not  wiped 
with  a  damp  cloth  previous  to  milking.  This  fact,  no  doubt,  at  least 
partially  accounts  for  the  high  numbers  of  bacteria  found  in  this  lot 
of  milk. 


EXPERIMENTS    AT    FARM    NO.    2. 


THIRD    TREATMENT    OK    THE    MACHINES. 


49 


After  being  washt  as  previously  described,  the  rubber  tubes  and 
teat  cups  were  placed  in  water  and  boiled  for  three-quarters  of  an 
hour.  They  were  then  hung  up  in  the  open  air  until  needed  for  the 
next  milking.  Just  before  using  they  were  rinsed  as  in  the  previous 
experiments  by  having  boiling  water  pumped  thru  them.  Table  1:4 
gives  the  results  of  four  tests  taken  with  the  machines  thus  treated. 

TAHLE  12. — Comparison  of  results  of  hand  and  machine  milking — machines  ringed  irith 
cold  water  and  washt  with  sal  soda,  then  boiled  for  tltree-quarters  of  an  hoar  and  ringed 
with  boiling  water  just  before  use. 


Date. 

No.  of 
experi- 
ment. 

Method  of 
milking. 

Bacteria  per  cubic  centimeter  of  milk. 

Total          Acid        IY.c?1,t    LilrlU,t;fy-    unique- 
bacteria,   bacteria,   i  „  ,ll;l!i«       tArin          fyinff 
bacteria. 

Hours  to  cur- 
dling at  — 

70°  F.     .50°  F. 

Julj 
Julj 
Julj 
Julj 

Ave 

''7 

f        29 
\        30 
\        35 
\        36 
f        39 
i        40 
f        47 
i        48 

Machine 
Hand.... 
Machine 
Hand.... 
Machine 
Hand.... 
Machine 
i  Hand  

[Machine 
\Hand  

18,737 

5,  612 
6,  537 

85,  700 
7,  175 

3,025 
125 

50 
462 
82,  950 
75 

16 
10 
1 
7 
97 
1 

612 
137 
100 
50 
1,750 
2,  200 

3 

18 
2 
1 

3 

91 
«126 
144 
a  54 

((78 
50 
"54 
52 

74 
a  150 
"54 
a  126 

134 
87 
«  102 
171 

28  

29  . 

10,  350 

3,  050 

30 

1,000 

9 

36,  683 
6,211 

28,675    .. 

1,231 

91 
71 

91 
133 

985    .  . 

847 

1 

"Curdled  at  night— exact  time  not  determined. 

This  increased  treatment  of  the  machine  apparently  was  not  sufficient 
to  greatly  change  the  quality  of  the  machine-drawn  milk.  However, 
in  experiment  o~>  the  number  of  bacteria  in  the  machine-drawn  milk 
was  somewhat  less  than  in  the  corresponding  hand-drawn  sample.  It 
should  be  borne  in  mind  that  the  numbers  of  bacteria  obtained  by  the 
hand  milking  are  extremely  low  for  milk  drawn  into  an  ordinary  open 
pail.  These  low  numbers  of  bacteria  found  in  the  hand-drawn  milk 
emphasize  the  fact  that  the  atmosphere  in  the  stable  was  relatively 
free  from  organisms,  and  that  considerable  care  was  exercised  in  the 
drawing  and  handling  of  the  milk.  The  man  who  did  the  milking  was 
unusually  careful  in  all  his  operations.  In  experiment  o!J  the  rubber 
tube  connecting  the  pulsator  with  the  stanchion  cock  was  not  boiled 
with  the  other  tubes,  and  it  is  probable  that  this  furnished  the  source 
of  contamination  and  explains  the  very  high  number  of  bacteria  in  this 
lot  of  milk.  In  order  to  determine  whether  the  rubber  tubes  were 
responsible  for  the  larger  numbers  of  bacteria  in  the  machine-drawn 
milk  a  new  set  of  tubes  was  used  in  experiments  (>:->  and  (!!).  These 
new  tubes  were  washt  and  then  scalded,  together  with  the  rest  of  the 
machine,  just  be- fore  using.  This  resulted  in  a  smaller  number  of 
bacteria  from  the  machine-drawn  milk  than  had  been  previously 
obtained. 


50 


THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 


TABLE  13. — Comparison  of  results  of  hand  and  machine  milking — new  tubes  and    teat 
cupx  used,  and  machines  washt  as  nsual  and  scalded  just  before  using. 


Date. 

Num- 
ber of 
experi- 
ment. 

Bacteria  per  cubic  cent 

meter  of  n 

Liquefy- 
ing bac- 
teria. 

lilk. 

Hours  to  cur- 
dling at— 

Method  of 
milking. 

Total 
bacteria. 

Acid 
bacteria. 

Per  cent 
of  acid 
bacteria. 

I'er  cent 
of  lique- 
fying 
bacteria. 

70°  F. 

50°  F. 

August  '2 

1        (13 

Machine 
Hand... 
Machine 
Hand... 

/Machine 
(Hand... 

3.  625 
650 
M,637 
1,344 

162 
275 
925 
150 

4 
42 
58 
12 

S7 
25 
25 
144 

2 
4 

1 
11 

86 
161 
50 
a  102 

a  126 
206 
116 
•i  126 

August  3.  .. 

••  \         64 
|        ti9 

Averages  .  . 

•  '  \        70 

2,631              543 
j            997              212 

55 

68 
132 

121 
166 

"Curdled  at  night— exact  time  not  determined. 


wo  jets  of  foremilk  removed. 


The  results  of  these  tests  as  shown  in  Table  13  would  make  a  very 
good  showing-  for  the  machine  were  it  not  for  the  fact  that  the  num- 
bers in  the  hand-drawn  milk  were  so  extreme!}'  low.  However,  it 
ought  to  be  possible  to  obtain  milk  by  means  of  the  machine  which 
would  contain  a  lower  germ  content  than  hand-drawn  milk  under  the 
same  conditions  provided  the  parts  of  the  machine  thru  which  the 
milk  past  were  sterile  at  the  outset,  since  the  milk  drawn  by  means  of 
the  machine  is  entirely  shut  off  from  external  contamination.  It  ought 
to  be  possible  to  obtain  the  milk  in  the  pail  with  practically  nothing 
but  the  bacteria  which  exist  in  the  udder.  This  manifestly  was  not 
the  case  with  the  trials  made  thus  far  and  it  was  evident  that  still 
greater  care  was  necessary  in  order  to  completely  sterilize  the  machines. 

In  order  to  determine  the  real  condition  of  the  inside  of  the  tubes  a 
test  was  made  at  this  point  to  rind  out  whether  or  not  the  inside  of  the 
rubber  tubes  was  being  sterilized  by  the  treatment  given  them.  A  small 
quantity  of  sterilized  water  was  run  into  the  central  part  of  the  long 
rubber  tubes  and  rinsed  back  and  forth.  This  was  then  poured  out 
and  a  drop  of  this  water  inoculated  into  a  gelatin  plate.  This  resulted 
in  the  development  of  1.728  colonies  of  bacteria  as  the  germ  content 
of  a  single  drop  of  the  water  used  for  rinsing  the  tube.  This  showed 
beyond  a  doubt  that  the  inside  of  the  tubes  was  not  being  properly 
cleansed  and  sterilized  by  the  treatment  thus  far  used  and  that  greater 
care  was  necessary  in  order  to  overcome  this  trouble. 

KOl'KTH    TREATMENT    <>F    THE    MACHINES. 

The  writer  desired  especially  to  test  the  efficiency  of  the  machine 
for  the  production  of  sanitary  milk,  or  milk  containing  a  minimum 
germ  content.  It  was  therefore  decided  to  take  still  more  vigorous 
moans  for  cleansing  and  sterilizing  the  machines.  To  do  this,  in  addi- 
tion to  the  treatment  usually  given,  the  tubes  were  boiled  for  three- 
quarters  of  an  hour  in  water  containing  a  small  quantity  of  powdered 
borax.  Thev  were  then  thorolv  rinsed  with  boiling  water  to 


EXPERIMENTS    AT    FARM    NO.   2. 


51 


remove  any  traces  of  borax  which  might  be  in  the  tubes.  A  small 
amount  of  borax  was  also  added  to  the  water  used  for  wiping  off  the 
udders.  In  addition  to  these  precautions  a  small  amount  of  foremilk 
was  also  drawn  before  attaching  the  machine  to  the  cows,  and  the  pail 
was  carried  out  of  the  stable  before  the  cover  was  removed.  This 
treatment  proved  to  be  more  effective  than  any  previously  given,  as 
will  be  seen  b}<  a  study  of  Table  14. 

TABLE  14. — Comparison  of  results  of  hand  and  machine  milking — machines  rinsed  with 
cold  water,  washt  with  warm  water  containing  sal  soda,  boiled  three-quarters  of  an  hoar 
in  water  with  borax,  and  scalded  just  before  use;  udders  wiped  with  borax  water. 


Date. 

exDeri    Mctho<1  of 
mePn[.'"    milki'^ 

Bacteria  per  cubic  centimeter  of  milk. 

Hours  to  cur- 
dling at— 

Total 
bacteria. 

A    -j        Percent 

bacteria      of  «cid 
bacteria.   bacteria_ 

Liquefy- 
ing bac 
teria. 

Per  cent 
of  lique- 
fying 
bacteria. 

i 
70°  F.      50°  F. 

.                           I        75     Machine  . 
Aug»st  4  \        76     Hand.   .  . 

iiurnsr  5           i       sl      Machine  . 
Au«ust  5  \        82     Hand...  . 
•t        87     Machine  . 
I        88     Hand... 

Averages    .                   (Machine  . 

462 
1  550 
400 
-     881 
612 
1  ,  300 

62  i          115 
49             139 
123  :      (a) 
^54  ,      (a) 
1>7S             124 
48             100 

225  ,               15 
12                   3 
81                  9 
112                18 
75                  (i 

419 

25 
0 
37 

80 

28 
6 
0 
6 
6 

506 
1,090 

62    

31 
40 

88             120 
50  i           120 

IHand.  ..   . 

78    

a  Not  curdled  by  August  19. 


''Curdled  at  night— exact  time  not  determined. 


It  will  be  noticed  in  this  table  that  the  machine-drawn  milk  con- 
tained in  each  case  much  smaller  numbers  of  bacteria  than  did  the 
corresponding  hand-drawn  milk.  These  numbers  compare  very  favor- 
ably with  the  germ  content  of  the  best  grades  of  "'sanitary"  or 
''clinical''  milk  which  are  now  placed  upon  the  market.  In  fact  these 
numbers  are  below  the  germ  content  of  much  of  such  milk.  The 
results  of  these  tests  are  sufficient  to  prove  that  the  germ  content  of 
milk  can  be  reduced  to  a  very  low  figure  by  the  use  of  the  machine 
when  properly  sterilized.  While  the  boiling  in  borax  water  was 
apparently  an  effective  treatment,  attention  should  be  called  to  the 
danger  of  using  this  or  other  antiseptics  to  rid  the  rubber  tubes  and 
teat  cups  of  bacteria.  A  very  thoro  rinsing  of  the  tubes  is  necessary 
in  order  to  remove  all  traces  of  the  antiseptic  so  that  none  of  it  can  be 
taken  up  by  the  milk  as  it  passes  thru  the  machine.  If  the  antiseptic 
were  left  in  the  tubes  it  would  be  the  same  in  effect  as  treating  the 
milk  with  a  preservative— a  practise  that  is  considered  very  objection- 
able. There  was  also  some1  question,  in  regard  to  the  effect  of  the 
boiling  upon  the  life  of  the  rubber  tubing,  and  it  was  some  work  to 
boil  the  machines  in  this  way  each  clay.  For  these  reasons  it  was 
thought  desirable  to  find  a  simpler  way  of  sterilizing  the  machines  and 
one  which  would  not  have  an  injurious  effect  upon  the  rubber. 


52          THK    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 


FIFTH    TREATMENT    OF    THE    MACHINES. 


Common  salt  is  a  good  germicide,  and  it  also  has  a  hardening  and 
preservative  effect  upon  the  rubber.  It  was  therefore  thought  that 
possibly  a  brine  solution  might  be  used  for  sterilizing  the  rubber  tubes 
instead  of  boiling  them  in  borax  water.  To  test  this  the  machines  were 
washt  as  usual,  after  which  all  the  rubber  parts  were  placed  in  a  moder- 
ately strong  brine  solution,  where  they  remained  until  needed  for 
the  next  milking.  Before  being  used  the^y  were  thoroly  rinsed  by 
having  boiling  water  pumped  thru  them.  Table  15  gives  the  results 
of  the  tests  made  with  the  machines  thus  treated. 

TABLK  15. — Comparison  of  results  of  hand  and  machine  milking — machines  being  washt  as 
usual,  the  rubber  parts  then  placed  in  brine  till  needed,  and  scalded  just  before  rise. 


Date. 

No.  of 
experi- 
ment. 

Method  of 
milking. 

Bacteria  per  cubic  centimeter  of  milk. 

Hours  to  cur- 
dling at  — 

Total 

bacteria. 

Acid 
bacteria. 

Per  cent 
of  acid 

bacteria. 

Liquefy- 
ing bac- 
teria. 

Percent 

of  lique- 
fying 
bacteria. 

70°  F. 

50°  F. 

August  7 

1        98 

Ma 
Ha 
Ma 
Hi 
Mi 
Hi 

fMi 
IHi 

chine., 
id  
thine., 
id  
'hine.. 
id  

thine., 
ul  

6,  450 
4,075 
400 
600 
483 
18,750 

475 
5G2 
112 
100 
100 
1  ,  350 

7 
11 

28 
1(1 
•21 

(525 
363 
100 
0 
33 
1,  149 

10 
9 

"o 

8 

52 
«  54 
48 
08 
101 
"78 

100 
"  102 
109 
121 

C'i 

I'O 

August  s 

•  \        94 
I        1)9 

\ugust  y 

•  i     100 

j       105 

•  \     loo 

2,  444 
11,712 

229 

1  ,  000 

2r>3 

67 

(17 

105 
112 

604 

('Curdled  in  night — exact  time  not  determined. 


''Not  curdled  August  19. 


It  will  be  noticed  that  in  experiment  !>•>  the  number  of  bacteria  was 
decidedly  higher  than  in  the  preceding  test*  given  in  Tables  13  and  M, 
while  in  experiments  9i)  and  105  they  were  as  low  as  when  the  machine 
was  treated  with  borax.  Probably  the  higher  number  in  experiment 
93  was  due  to  the  fact  that  only  part  of  the  rubber  tubes  were  treated 
with  the  brine  solution,  while  on  other  days  all  the  rubber  parts  were 
placed  in  the  brine.  It  would  seem  from  the  results  of  these  tests 
that  the  brine  treatment  is  as  effective  as  the  boiling  in  borax  water 
and  is  at  the  same  time  much  simpler. 


SIXTH    TREATMENT    OF    THE    MACHINES. 


The  usual  method  for  sterilizing  dairy  utensils  is  by  steam.  This  is 
entirely  satisfactory  with  ordinary  dairy  utensils,  but  steam  is  known 
to  have  an  injurious  effect  upon  rubber,  for  which  reason  steam  ster- 
ilizing \vas  not  generally  used  in  this  series  of  experiments;  but  at  this 
point  it  was  doomed  desirable  to  compare  the  efficiency  of  steam  ster- 
ilizing with  the  treatments  previously  given,  in  order  to  determine 
whether  or  not  it  was  possible  to  reduce  still  further  the  germ  content 
of  the  machine-drawn  milk.  To  accomplish  this  a  large  wooden  box 


EXPERIMENTS    AT    FARM    NO.    2. 


53 


was  fitted  up  to  serve  as  a  steam  sterilixer.  After  the  machine  had 
been  washt  as  usual,  it  was  placed  in  this  box'  and  subjected  to  live 
steam  for  30  minutes.  Table  16  gives  the  results  of  this  series  of  tests. 

TAHLE  1<>. — Comparison  of  results  of  hand  and  machine  milking — machines  washt  as 
usual  and  sterilized  in  steam  for  thirty  minutes. 


Bacteria  per  cubic  centimeter  of  milk. 

Hours  to  cur- 
dling at  — 

Date. 

ber  of     Method  of 
experi-    milking. 
merit. 

Total 
bacteria 

Acid 
bacteria. 

Per  cent 
of  acid 
bacteria. 

1  ioiiffv   '  1>er  cent 
ing        of  lique- 

70°  F. 

50°  F. 

August  10  

/      111     Machine.. 
1      112     Hand... 

560 
400 

37 
112 

7 
28 

0 

77 
158 

gj 

75                19 

.                         ,1      117     Machine.. 
A"SUS1  u  \      118     Hand  

1,  962 
1,762 

337 

375 

18 
22 

75                   4 
287                17 

69 
'•30 

60 

AUS-U2  {      }»     Machine. 

1,087 
850 

137                14 
100                12 

75                   7 
112                 13 

45 
49 

(«j 

Aup-tu  {  ijg  Sh:e: 

9,887 
5,  540 

225                  2 
860                10 

375                   4 
250  I                5 

<«) 

(«i 

<      ,,  ,  1.            (      135     Machine  . 

3,  750 

387                 10               162                   4 

ft  54 

(") 

••  I      136     Hand...   . 

1,337 

362                 28               275                 21 

(«) 

(«) 

Average-; 

.(Machine.  . 

3,449 

1,978 

225 

362 

137    

64 

••  \Haud  

200    

79 

n\ot  curdled  August  19. 


Curdled  at  night — exact  time  not  determined. 


It  will  be  noticed  that  in  each  test  the  machine-drawn  milk  contained 
larger  numbers  of  bacteria  than  did  the  corresponding-  hand-drawn 
sample.  It  was  impossible,  with  the  equipment  used,  to  get  any 
pressure  in  the  steam  chest,  hence  the  temperature  did  not  quite  reach 
the  boiling  point  (212°  F.).  Under  these  conditions  it  is  probable 
that  the  inside  of  the  rubber  tubes  did  not  become  heated  to  the  tem- 
perature of  the  steam,  and  they,  therefore,  were  not  sterilized  during 
the  thirty  minutes  that  they  were  subjected  to  the  steam  treatment. 
Probably  a  longer  steaming  might  prove  effective,  but  it  is  evident 
that  the  treatment  here  given  was  not  sufficient  to  completely  sterilize 
the  tubes.  The  rubber  tubing  did  not  appear  to  be  seriously  injured 
by  the  steam  treatment  during  this  series  of  tests,  but  it  is  quite  prob- 
able that  long-continued  steam  sterilizing  would  injure  the  rubber. 
This  series  of  tests  would  at  least  indicate  that  it  is  necessary  to  sub- 
ject the  tubes  to  greater  steam  pressure  or  else  use  other  germicides 
in  order  to  completely  sterilize  the  rubber  tubing.  At  the  close  of 
this  period  one  test  was  made  by  treating  the  machine  in  brine,  as 
alreadv  described.  The  results  of  this  test  are  shown  in  Table  IT. 


TABLE  17.  —  Comparison  of  results  of  ham!  and  machine  milking — machine*  t/-rate<i  a*  i/uli- 


cated  lor  Table  15. 


Bacteria  per  cubic  centimeter  of  milk. 


experi-    milking.        ...      ,  .  ..,        Percent    Liquefy-      ,-!• 

Intal          Acid  ..      .,,      .     '  ,     •      fit  haul 


54          THE    MILKING    MACHINE    AS    A    FACTOR    IN    DAIRYING. 

KEEPING    Ql'AUTIEH    OF    THE    MILK. 

The  discussion  of  the  keeping  qualities  of  the  milk  given  in  con- 
nection with  the  experiments  at  farm  No.  1  will  in  general  apply 
with  equal  force  to  the  results  obtained  at  farm  No.  2.  Practically 
the  same  results  were  obtained  in  both  cases.  In  the  majority  of 
instances  the  difference  in  keeping  quality  is  in  favor  of  the  machine- 
drawn  milk,  both  at  70°  and  50°  F.  This  difference  is  especially 
noticeable  in  Table  14.  where  the  germ  content  of  the  machine-drawn 
milk  averaged  the  smallest.  With  an  average  of  506  bacteria  per  cubic 
centimeter  the  milk  kept  on  an  average  eighty -eight  hours  at  70°  F. , 
while  the  hand-drawn  milk,  with  an  average  of  1,090  bacteria,  kept  an 
average  of  but  fifty  hours,  making  an  average  difference  of  thirty-eight 
hours  in  favor  of  the  machine-drawn  milk.  This,  at  least,  is  an  indi- 
cation of  the  extent  to  which  the  keeping  quality  of  the  milk  may  be 
improved  by  the  use  of  the  machines,  provided  they  are  kept  in  a 
sterile  condition  and  care  is  used  in  their  manipulation. 

SUMMARY  OF  RESULTS  OF  BACTERIOLOGICAL  INVESTIGATIONS. 

The  results  of  the  foregoing  experiments  seem  to  justify  the  follow- 
ing conclusions: 

1.  Unless  sufficient  care  is  used  in  cleaning  the  machines,  decaying 
milk  and  bacteria  accumulate  in  the  rubber  tubes  and  contaminate  the 
milk  as  it  passes  thru  them. 

2.  The  few  dairymen  now  using  these  machines  are  not  exercising 
sufficient  care  in  washing  and  sterilizing  the  machines  to  keep  them  in 
sanitary  condition:  their  milk  is  therefore  of  poorer  quality  from  the 
sanitary  standpoint  than  that  drawn  by  hand  under  the  same  stable 
conditions. 

.'-).  Good  sanitary  conditions  in  a  stable  may  be  completely  counter- 
acted by  the  insanitary  condition  of  the  milking  machine. 

4.  When  kept  in   fairly  clean   condition    the    machine-drawn    milk 
contains  decidedly  smaller  numbers  of  bacteria  than  the  corresponding 
hand-drawn  milk. 

5.  When  the   machines  are  not  well  cleaned  both  the  number  and 
percentage  of  acid-producing  bacteria  are  higher  than   in  the   hand- 
drawn  milk,  but  when  they  are  fairly  well  cleaned  both  the  total  num- 
ber and  the  percentage  of  these  bacteria  are  decidedly  lower  than  in  the 
corresponding  hand-drawn  milk. 

t>.  ]>oth  the  total  number  and  the  percentage  of  liquefying  bacteria 
found  in  the  milk  were  in  most  cases  greatly  reduced  by  the  use  of  the 
machines.  This  fact  is  of  special  significance  in  milk  designed  for 
direct  consumption. 

7.  When  properly  cared  for.  drawing  the  milk  by  means  of  the 
machine  increases  its  keeping  quality. 


SUMMARY    OF    BACTERIOLOGICAL    INVESTIGATIONS.  55 

8.  Washing  the  machines  with  cold  water  and  then  with  hot  water 
containing  sal  soda  is  not  sufficient  to  keep  the  rubber  tubes  clean. 
Under  this  treatment  the  inside  of  the  tubes  becomes  coated  with  decay- 
ing- milk,   thus   forming;  ideal    conditions   for   the    multiplication   of 
various  species  of  bacteria. 

9.  Scalding  the  machines  by  pumping  boiling  water  thru  them  just 
before  use  had  little  or  no  effect  in  reducing  germ  content  of  the  milk. 

11).   Boiling  in  clear  water  for  three-quarters  of  an  hour  was  not  suf- 
ficient to  keep  the  rubber  tubes  in  a  sterile  condition. 

11.  Subjection  to  steam  without  pressure  for  thirty  minutes  was  not 
sufficient  to  sterilize  the  rubber  tubes. 

12.  Placing  the  rubber  parts  in  brine  for  several  hours  after  being 
washt  reduced  the  germ  content  of  the  machine-drawn  milk  to  about 
one-half  that  of  the  milk  drawn  by  hand. 

13.  Boiling  in  water  containing  a  small  amount  of  powdered  borax 
had  about  the  same  effect  in  reducing  the  bacterial  content  of  the  milk 
as  did  the  brine  treatment,  but  the  use  of  borax  is  dangerous  unless 
extreme  care  is  exercised. 

14.  The  machines  may  be  veiy  effective  in  the  production  of  sani- 
tary milk  if  they  are  properly  cleaned  and  sterilized. 

15.  The  results  of  these  experiments  indicate  that  the  machines  may 
be  kept  in  such  an  insanitary  condition  that  the  keeping  quality  will 
not  be  improved,  but  may  be  seriously  impaired.     They  also  indicate 
that  with  properly  cleaned  and  sterilized  machines  the  keeping  quality 
of  the  milk  may  be  very  materially  improved. 

O 


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